How to look for records of... Naturalisation, registration and British citizenship

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1. Why use this guide?

Use this guide if you are looking for records of how, when or if a person obtained British citizenship up to October 1986.

For naturalisation certificates after 1 October 1986, and for records of indefinite leave to remain from any date, go to the United Kingdom Visa and Immigration Service.

Do not use this guide for legal advice. For questions about any living person’s rights and status in the UK you should contact the United Kingdom Visa and Immigration Service or seek legal advice from a solicitor. The National Archives cannot provide legal advice of any kind.

2. What is naturalisation?

Naturalisation is the legal process by which a person changes their nationality.

For hundreds of years, foreign nationals living in the UK, and sometimes living abroad, have been able to attain British citizenship through naturalisation.

The criteria and process have changed over the years but for successful applicants the end result has been the same: that person is granted the same legal rights and status of a natural-born British citizen.

Before 1844 naturalisation was granted only by a private act of parliament. The procedure was expensive and only a few could afford it. After 1844, right up to the present day, naturalisation has usually been granted by the Home Office.

3. What are registrations of British nationality?

From 1949, people in the British Commonwealth could register their British citizenship to remain British citizens – whether or not they actually moved to the UK. Up until 1949 citizens of any colony or dominion in the British Empire were automatically considered British subjects but this changed with the British Nationality Act 1948.

People born in Ireland before 1949 were, likewise, considered British subjects and after the 1948 Act could also register British nationality; however, anyone born in the Republic of Ireland after 1948, seeking British citizenship, would need to apply to naturalise.

Registrations ended in 1981 and from then on all foreign nationals, whether from the Commonwealth, former British colonies or any other country in the world, have had to apply for naturalisation to become British citizens.

4. Record types and the information they contain

The process of naturalisation or registration produces paperwork. Most of the surviving paperwork, up until 1986, for successful naturalisations is now held at The National Archives. There are two broad types: the document declaring someone’s naturalisation and the background papers that were submitted to support their application.

Image of a naturalisation certificate of Peter Santi from July 1957

Naturalisation certificate of Peter Santi from July 1957

4.1 Naturalisation certificates

Issued to all people who are granted British citizenship through naturalisation.

Usually naturalisation certificates contain:

  • full name
  • residence/address of applicant
  • birthplace
  • age/date of birth
  • parents’ names
  • name of spouse (if married)
  • occupation
  • children with their names and ages (if still of dependent age)

4.2 Indexes to naturalisation certificates

The Home Office indexes to naturalisation certificates cover 1908-1980. From June 1969 the Home Office did not keep a set of duplicate certificates issued in the UK for foreign nationals so the index is the only source of detail until 1980. The indexes contain:

  • name
  • place of residence
  • naturalisation number
  • date of issue

4.3 Naturalisation case papers

These are the forms individuals filled out when applying for naturalisation, though they rarely survive if naturalisation was not granted. These papers provide more detailed information on the applicant than the naturalisation certificate itself and may contain all or some of the following information:

  • nationality
  • profession
  • names and ages of spouse and children

    Image of a completed application form for a registration of British nationality from 1966

    A completed application form for a registration of British nationality from 1966

  • birth date
  • birth place
  • address of the applicant
  • character reference(s)
  • police report (after c1878)

4.4 Registrations of British nationality

Registrations issued before 1970 tend to be in the form of an application with information similar to naturalisation certificates. From 1970 they tend only to include the full name of the applicant, their date and place of birth.

4.5 Private Acts of Parliament

Before 1844 the only way to naturalise was through a private Act of Parliament. Often a single act, usually appearing on parchment rolls, covered multiple individuals and contained nothing more than their names and professions. Sometimes, however, you may find the names of the naturalised person’s parents and the place of birth, particularly in the case of acts passed for just a single individual.

5. Naturalisation, 1949-1986

This section covers records of foreign nationals becoming British citizens through naturalisation between 1949 and 1986. However, records of British citizenship after 1949 and up to 1981 for people from British colonies and Commonwealth countries, are more likely to be registrations of British nationality – see section 6 for advice on these records.

See section 4 for an explanation of what information the following types of records contain.

5.1 Naturalisation certificates and indexes 1949-1981

Search by certificate number or by name followed by nat* in our catalogue, using the box below, for naturalisation certificates (HO 334) and naturalisation certificate index entries (HO 409). From June 1969 the index is the only source of detail for foreign nationals who naturalised in the UK as the Home Office did not keep a set of duplicate certificates during this period. Sort your search results by date.

5.2 Naturalisation certificates 1981-1986 for people born less than 100 years ago

Apply for duplicate certificates through our Certificates of British citizenship page

5.3 Naturalisation certificates 1981-1986 for people born over 100 years ago

Search by certificate number or by name followed by nat* in our catalogue, using the box below.

5.4 Naturalisation case papers to 1996

Search our catalogue, using the box below, by last name for naturalisation case papers (HO 405).





 Not all documents in HO 405 are open to view. The documents are subject to 100 year closure (although you can requested access with a Freedom of Information request) and only about 40% of applications in this series have survived. Files may also contain later correspondence, mostly until the mid-1960s but some as late as 1996.

6. Registrations of British nationality, 1949-1981

The British Nationality Act 1948 created the new status of citizen of the United Kingdom and the colonies. Under this act, people from former colonies and British Commonwealth countries could register as British citizens.

See section 4 for details of the information that records of registration contain.

6.1 Registrations of British Nationality 1949-1981 for people born less than 100 years ago

Apply for duplicate certificates through our Certificates of British citizenship page.

6.2 Registrations of British Nationality 1949-1981 for people born over 100 years ago

Search by certificate number or by name followed by reg* in our catalogue, using the box below.

7. Renunciations and no evidence of naturalisation

Among the records of naturalisation sent to The National Archives from the Home Office are records of people who have renounced their British citizenship.

7.1 Records of the renunciation of British citizenship 1949-1982

Search by name followed by the word ‘renunciation’ in our catalogue, using the box below.


7.2 No evidence of naturalisation

Some people, usually resident in the UK, want to prove that they were never naturalised. The National Archives can help to prove this only by first searching for a naturalisation certificate. If our search is unsuccessful we can provide a ‘letter of no evidence’.

If you would like us to send you a letter of no evidence you will first need to request a search for a certificate of British citizenship.

8. Naturalisations, 1870-1948

This section covers records of foreign nationals becoming British citizens between 1870 and 1948. The 1870 Nationality Act superseded the 1844 Nationality Act which governed naturalisations up to 1869.

8.1 Naturalisation certificates 1870-1916

Search by name in record series HO 334 on Ancestry.co.uk and download (£) naturalisation certificates and declarations of British nationality for these years.

However, certified copies are available only from The National Archives. If you need a certified copy of a certificate from this period you can request one from our online catalogue. Search for a certificate in records series HO 334 and HO 409 by certificate number or by name followed by nat* using the box below:

8.2 Naturalisation certificates from 1913-1948

Search by certificate number or by name followed by nat* in record series HO 334 and HO 409 using the box below.

8.3 Naturalisation case papers 1872-1934

Search by name followed by nat* in our catalogue, using the box below, for case papers (HO 45, HO 144, HO 382).

8.4 Naturalisation case papers from 1934

Search our catalogue, using the box below, by last name for case papers (HO 405).





The documents are subject to 100 year closure (although access can be requested using our Freedom of Information form) and only about 40% of applications in this series have survived. Files may also contain later correspondence, mostly until the mid-1960s but some as late as 1996.

See section 4 for an explanation of what information naturalisation certificates and case papers contain.

8.5 Private Acts of Parliament

The original private acts of Parliament are kept at the Parliamentary Archives, though there are very few naturalisation acts after 1844.

There are some records of naturalisations from this period at The National Archives among the following records:

  • Parliament Rolls in C 65

9. Naturalisations, 1801-1873

Most foreign settlers in the UK before 1844 did not bother going through the legal formalities of naturalisation and so do not appear in these records. Before 1844 the only way to naturalise was by a private Act of Parliament.

9.1 Naturalisations on close rolls 1844-1873

Naturalisations during this period were recorded, or ‘enrolled’, on documents known as close rolls. The close rolls are in record series C 54.

To work out which pieces in C 54 to look at you will need to first consult the printed index to C 54 which itself forms a separate series, C 275. The index is arranged by year so you will need at least a rough idea of when the naturalisation took place (look at the correspondence and case papers in HO 1 first if you don’t know the year of naturalisation).

To use the index and view the rolls themselves you will need to visit us. On consultation of the appropriate section of the index you may find a name entry for the person who was naturalised, along with a number that will form the key part of your C 54 reference. For more advice speak to staff in the Map and Large Document Reading Room at our building in Kew.

9.2 Naturalisation case papers 1801-1871

Search and download (£) naturalisation case papers (HO 1) for 1801-1871 from our catalogue.

See section 4 for an explanation of what information naturalisation certificates and case papers contain.

9.3 Private Acts of Parliament

The original private acts of Parliament are kept at the Parliamentary Archives, though there are very few naturalisation acts after 1844.

There are some records of naturalisations from this period at The National Archives among the following records:

  • Parliament Rolls in C 65

10. Naturalisations before the 19th century

The only way to naturalise before the 19th century was by a private Act of Parliament, though there were occasionally public acts passed to enable the naturalisation of specific groups of people at specific times, as was the case for foreign protestants living in America in the mid-18th century (see below).

10.1 Private Acts of Parliament

The original private acts of Parliament are kept at the Parliamentary Archives. However, there are some records of naturalisations before the 19th century at The National Archives among the following records:

  • Parliament Rolls in C 65

10.2 Oaths of allegiance

After a naturalisation by Act of Parliament the successful applicant would take the Oath of Allegiance and Supremacy in a court of law, swearing their loyalty to the Crown. There are separate sets of records for these oaths and where to locate them depends on the court where the oath was taken. Quarter Sessions Courts and the Court of Kings Bench were among those courts where the oath was taken:

  • Oath Rolls in KB 24
  • An oath roll for naturalisation of protestant refugees 1709-1711 in E 169/86
  • Quarter Sessions court record, held at local archives

10.3 Foreign protestants living in America 1740-1772

Between 1740 and 1772, foreign protestants living in America could become naturalised British citizens after seven years’ residence. Over 7,000 foreign protestants took advantage of this.

Every year lists of those naturalised were sent to the Commission for Trade and Plantations in London, where they were copied into entry books.

A list of the names in these records is in the published Naturalizations of Foreign Protestants in the American and West Indian Colonies, also available in our library.

10.4 Indexes

The Huguenot Society have published indexes to the records of naturalisations and denizations up to 1900. Some of these indexes are available online on the Internet Archive:

Some of the indexes are also available in our library:

Versions of these indexes are held with the printed version of our catalogue at our building in Kew.

11. Denization records, c.1200-1873

11.1 What was denization?

Denization was a legal process granting limited naturalisation to aliens. It granted a foreign national almost equivalent status of native-born Britons and provided them the protection of the law.

However, those granted denization were still subject to alien rates of tax, unable to vote, hold civil or military office or inherit land.

Denization was granted by letters patent and this required a payment, so, as with naturalisation in this period, denization remained the preserve of the wealthy.

11.2 The records

Click on the references below to search by name of applicant for denizations made by letters patent in:

Use the Huguenot Society Indexes and Calendars of Patents Rolls at The National Archives in Kew, looking under words such as ‘denizations’ or ‘indigenae, to search for denizations made by letters patent in:

  • the patent rolls in C 66
  • the supplementary patent rolls in C 67 (1275-1749)

12. Records in other archives

12.1 Huguenot Society records

Consult the Huguenot Society website, which includes information about their archives and details of publications to help you trace individual immigrants (not just Huguenots), including indexes of naturalisations by private Act of Parliament up to 1800.

12.2 Parliamentary papers

The original naturalisation acts are kept at the Parliamentary Archives.

Search Parliamentary papers (institutional subscription required) for indexes of all naturalisations from 1844 to 1961.

12.3 Westminster denization roll

This is held at Westminster Abbey Muniments and Library.

13. Appendix: prefixes to naturalisation certificate and registration numbers

If you know the naturalisation certificate number then you can use the following tables to determine details about the status of the person who applied for naturalisation. The table may also help you work out what you should do to search for a duplicate copy of the certificate.

13.1 Naturalisation certificates issued under the terms of the Naturalisation Act, 1870 and the British Nationality and Status of Aliens Act, 1914

Those issued under both the Naturalisation Act, 1870, and the British Nationality and Status of Aliens Act, 1914, are searchable by name in Discovery, our catalogue.

Naturalisation Act, 1870
A Certificate (ordinary) to a person with five years residence in the United Kingdom during the eight years immediately preceding application for Naturalisation
AA Certificate to person with five years service under the Crown during the eight years immediately preceding application for Naturalisation
AAA Certificate to person in the Diplomatic or Consular Service with five years service under the Crown during the eight years immediately preceding application for Naturalisation
B Certificate to person who has already been granted a Certificate of Naturalisation under the Act of 1844
C Certificate to a person of Doubtful Nationality with five years residence in the United Kingdom, or five years service under the Crown, during the eight years immediately preceding application for re-admission
D Certificate of re-admission of person to British Nationality with five years residence in the United Kingdom, or five years service under the Crown, during the last eight years immediately preceding application for re-admission
E Declaration made by a person, a subject of a foreign state subsequently naturalised as a British subject, renouncing British nationality
F Declaration by a person, an alien by origin but born within HM dominions, renouncing British nationality
G Declaration by a person, born out of HM dominions of a father being a British subject, renouncing British nationality
H Declaration by a natural-born British subject, renouncing subsequent Naturalisation in a foreign state
British Nationality and Status of Aliens Act, 1914
A and AZ Certificate (ordinary) granted under Section 2 of the Act, where the names of children are not included
B and BZ Similar to Certificate A, but including the names of children
C and CZ Certificate granted under sub-section (2) of Section 5 of the Act to a minor
D Special certificate granted under Section 4 of the Act to a person with respect to whose nationality a doubt exists, where the names of children are not included
DZ Certificate of Naturalisation granted to a woman who was at birth a British subject and is married to a subject of a state of war with His Majesty
E Similar to Certificate D, but including the names of children
EZ Similar to Certificate DZ, but including the names of children
F Certificate granted under Section 6 of the Act to a person naturalised before the passing of the Act, where the names of children are not included
FZ Certificate of Naturalisation granted to a French national where the names of children are not included
G Similar to Certificate F, but including the names of children
GZ Similar to Certificate FZ, but including the names of children
M Special Certificate granted under Section 4 of the Act to a person with respect to whose nationality a doubt exists
O Certificate granted under Section 8 of the Act by the Government of a British Possessions overseas

13.2 Naturalisation certificates and registrations issued under the terms of the British Nationality Act, 1948

British Nationality Act, 1948
BNA Application made by a subject of a foreign state resident in the UK – search by name on Discovery, our catalogue for the dates 1949-1971
M s7 & 18 1948 Act: application for registration of a minor child – submit a search request using our contact form for the dates 1949-1972
O Application made by a subject of a foreign state resident overseas – search by name on Discovery, our catalogue for dates 1949-1980
R1 s6(1) 1948 Act: application made by an adult British subject or citizen of the Republic of Ireland, or any of the Channel Islands, Isle of Man, a colony, a protectorate or a protected state to which s8(1) of the Act applied, or a UK Trust Territory, or on the grounds of Crown Service under HM Government in the UK – submit a search request using our contact form for the dates 1949-1972
R2 s6 (2) 1948 Act: application made by a woman who has been married to a citizen of the UK and colonies – submit a search request using our contact form for the dates 1949-1972
R3 s6 (2) 1948 Act: application made by a woman who has been married to a citizen of the UK and colonies – submit a search request using our contact form for the dates 1949-1972
R4 s12 (6) 1948 Act: application made by a person who but for his citizenship or potential citizenship of one of the countries mentioned in s1 (3) of the Act would have become a citizen of the UK and colonies under s12 (4) of the Act- submit a search request using our contact form for the dates 1949-1951
R5 s16 1948 Act: application to resume British nationality by a person who has ceased to be a British subject on the loss of British nationality by his father or mother in accordance with s12 (1) of the 1914 Act- submit a search request using our contact form for the dates 1949-1959
R6 s19 1948 Act: declaration of renunciation of citizenship made by a citizen of the UK and colonies who is also a citizen of one of the countries mentioned in s13 of the Act or of the Republic of Ireland or a national of a foreign country- submit a search request using our contact form for the dates 1949-1982

13.3 The British Nationality Act 1971

For 300,000 to 999999: Application for naturalisation – submit a search request using our contact form for dates 1973-1982.

13.4 The British Nationality Act 1981

1,000,000 plus: Application for naturalisation – submit a search request using our contact form for dates 1983-1986.

14. Further reading

Some or all of the publications below may be available to buy from The National Archives’ bookshop. Alternatively, search The National Archives’ library catalogue to see what is available to consult at our site in Kew.

Roger Kershaw, Migration Records: A Guide for Family Historians (The National Archives, 2009)

Roger Kershaw and Mark Pearsall, Immigrants and Aliens: A Guide to Sources on UK Immigration and Citizenship (The National Archives, 2004)

Guide reference: Domestic Records Information 49