Henry Richard Yeoville Thomason (1826-1901) was born in Edinburgh, but came of an established Birmingham family: his grandfather was Sir Edward Thomason, the medal list (1769-1849). He became a pupil of the leading Birmingham architect Charles Edge, who had completed the Town Hall after the bankruptcy of the original architects, Hanson & Welch, and whose drawings are also preserved in the Library. In about 1853 or 1854 he set up in practice on his own, initially at 64 New Street but by late 1854 at Wellington Chambers, 40 Bennetts Hill, near to Edge's office at no 18, Bennetts Hill. At first he practised as H.R Yeoville, but by 1860 he was using his full name.
Thomason's connections within the City soom provided him with regular work, and between 1874 and 1884 he was almost continuously engaged on the construction of the Council House and the first extension to it, comprising the Art Gallery and the Gas Department. From soon after he had qualified he managed the architectural department of the borough surveyor's office, and public architecture was well suited to his taste for rather florid Italianate design. Towards the end of his career he became architect to the Birmingham, Dudley & District Banking Co., and the collection contains designs for several banks in and around the West Midlands.
Cooper Whitwell was in practice at 40 Bennetts Hill by 1883, but not until 1887 do the names Thomason & Whitwell appear linked in partnership: they moved in the same year to 1 Cannon St. Whitwell seems to have undertaken almost all the firm's work, however, and Thomason went into retirement. He died in London in 1901. Whitwell dropped the pretence of a partnership in 1894, and by 1899 the firm had become C Whitwell & Son., which it remained until its dissolution in 1953: latterly the partners were William A. Whitwell and Arthur W. Whitwell. From 1899 it was based at 23 Temple Row, by 1923 it had moved to 9 Newhall St and in the following year it moved again to 3 Newhall St. In 1952 the Whitwell brothers apparently abandoned their town office and continued the practice from their home address, Newborough House, Newborough Road, Shirley, for a further year.