as he was an intellegence officer - he couldn't write about actual stuff in the offices in Britain (M was actually C) - but he could write about inside information of other agencies (adding an extra element for those in the know).

The NSA says that SMERSH existed -

An interesting Naval GRU message, No. 682, 13 April 1942, Stockholm to Moscow, describes a German peace initiative to the banker Jakob Wallenberg, uncle of Raoul Wallenberg, the Swedish diplomat and humanitarian. No translation in the VENONA material, however, is known to concern the case of Raoul Wallenberg, who was arrested by SMERSH (Military Counter- intelligence) in Budapest in 1945 and was reportedly murdered by the KGB in Moscow. Examples of other Stockholm messages:

[link|http://www.nsa.gov/docs/venona/monographs/monograph-5.html| NSA ]