This facinating article from 1950. John Peet went on to edit the hugely influential Democratic German Report and contribute occasionally on RBI. I have a cartoon drawing of him from the 20th anniversary issue of DGR which I plan to scan and upload (when I can get to a scanner). I was privalaged to meet him as a young teenager in 1972.
Time Magazine - Monday, June 26, 1950
D'ye Ken John Peet?
To his friends and acquaintances, shy, scarecrow-thin John Peet was not easy to ken. At 34, he had gone through an odd succession of careers: enlisted man in Britain's crack Brigade of Guards, English teacher in Prague, private in the Spanish Civil War's International Brigade, policeman in Palestine, chief Berlin correspondent for Reuters news agency. Some people considered John Peet insecure, haunted and unhappy; others regarded him as witty, well-informed and likable. Allied officials in Berlin had privately marked him down as a Communist or at least a fellow traveler, who passed information to the East Germans in exchange for news beats, but his Reuters bosses considered Peet a nonpolitical man who filed factual dispatches and never picked sides.
Last week Newsman Peet picked sides. At a press conference staged by Communist Propagandist Gerhart Eisler in the Soviet sector of Berlin, Peet charged the Western Allies and their press with "distortions" and "warmongering." Then he asked the Communist government of East Germany to let him stay there.
In Britain, the defection was Page One news. Even so, one news agency threw away a good eyewitness account of the press conference. Under the circumstances explained Reuters, that seemed the best thing to do: it had been filed by John Peet.
jackfrost
Pro 
From 1952 to 1975, Peet produced the Democratic German Report, a newsletter targeting the left-of-centre public opinion in the UK. His positive portrayal of the GDR was among the GDR's most believable and powerful propaganda in Britain. He spent the last ten years of his life translating Marx and Engels into English. Many East Germans saw Peet as the archetypical Englishman, and he played this character in several East German films. In his posthumously published memoirs, Peet writes about his defection (at the time, he stated he "could no longer serve the Anglo-American warmongers ...") as well as his links to Soviet intelligence.
Peet was married three times and had two children.