about German espionage methods from MI5 interviews with Sergueiew, November
(Catalogue reference: KV 2/464)
4. For the other method shown her by DELIDAISE, SERGUEIEW was
to take what looked like an indelible copying pencil and with it scribble
on a sheet of paper so that one side of it was completely covered. This
sheet of paper was then used as a carbon. It apparently left no trace
on the sheet of paper underneath.
5. Yvonne DELIDAISE took away SERGUEIEW’s experiments in both
these methods of secret writing, saying that she would have them developed.
SERGUEIEW, however, never saw the results and can give no more information.
6. The final method of secret writing in which SERGUEIEW was instructed
was that given her for her mission to this country. For this she was to
use the pellets given her by KLIEMANN before her departure from Paris
(see para.112 1st Report). She was instructed in their use in the flat
at 29 Avenue de l’Opera (see para.109 1st Report).
7. A pellet was to be heated in a clear flame which would not discolour
it. When the pellet was melted she was to take a wooden toothpick and
dip it in the liquid. When it was dry she would re-dip it and continue
doing so until all the liquid had been absorbed and a new pellet reformed
on the end of the stick. This could now be used as [a] pen for her secret
writing. She would then take a sheet of paper (non-shiny surface) and
rub the paper evenly with cotton-wool. On the side she rubbed she was
to write her cover letter in ink or pencil, preferably the former. Her
letter in invisible writing was then to be written on the same side of
the paper but at right angles to the visible text. If SERGUEIEW used a
double sheet which entailed 4 written sides, the invisible writing was
only to be done on the first and third pages.
8. Her cover letter was to be signed “SOLANGE”. It was left
to her as to whether she made use of the code for her invisible writing,
but this was considered unnecessary.