Soviet spy Guy Burgess penned an optimistic letter to his mother, despite hating his time there.
Five years after disappearing from the Foreign Office in May 1951, Burgess wrote to her from a village outside Moscow.
Discussing plans for her to visit him, he urged her to come to the "hot Crimean/Black Sea 'Riviera"', suggesting they could spend the day on a private beach and "go for drives in the country and on the sea in speed boats".
He planned to furnish his flat with English furniture rather than "hideous" heavy Russian items, extolled the virtues of readily available smoked salmon and caviare and admitted he was getting "rather fat", which he attributed to the fact that "for the first time for about twenty years I'm not worried and not in a state of perpetual excitement and fuss".
Burgess told his mother the contrast between the "worry and anxiety in which everyone lived in London and more Washington and here is quite extraordinary", saying "people are full of optimism and hope instead of worry and fear".
He ended the letter, dated from October 1956 but thought to be from February that year, by saying: "Darling please don't think and don't let anyone else think that because I'm happy and flourishing I have ever been able to forget for a moment the unhappiness, disaster and worry I must have caused everyone."
The letter was in files released to the National Archives in Kew, west London.
Other letters from Burgess to friends revealed he was aware that MI5 were likely to be reading them - in one note to a friend, Peter Pollock, Burgess included a sketch of MI5 officers reading through his correspondence, perhaps making a wry point to his former colleagues.
While most of the communication is amicable, a letter from the RNLI turning down a subscription from Burgess curtly informed him: "We do not accept money from traitors."