[2][3] She moved to East Germany in 1950 when Fuchs was unmasked, and published a series of books related to her espionage activities, including her bestselling autobiography, Sonjas Rapport.

[7] Between December 1928 and August 1929 she worked in a New York book shop before returning to Berlin where she married Rudolf Hamburger, an architect and fellow member of the Communist Party.

[2] With her husband she relocated, in July 1930, to Shanghai[3] where a frenetic construction boom afforded ample opportunities for Hamburger's architectural work.

[7][14] In Fall 1931, she had to send her son Maik to live with her husband's parents (now relocated from Germany to Czechoslovakia) when she was sent to Moscow where she undertook a seven-month training session before returning to China.

[7] There had been a concern that if baby Michael had accompanied her to Moscow he might inadvertently have blown her cover later by blurting out words in Russian.

[7] Between Autumn 1938 and December 1940, as agent "Sonja Schultz", she was based, still with her husband Rudolf Hamburger, in Switzerland where she was one of the so-called "red three", together with Sándor Radó: her duties included working as a specialist radio operator, applying technical skills acquired during her Moscow visits earlier in the decade.

[7] In Switzerland, which was where her marriage with Rudolf Hamburger finally broke apart,[7] she collaborated with the Lucy spy ring and was involved in recruiting agents to be infiltrated into Germany.

[14] The Beurtons' Oxfordshire village homes were also close to the UK's Atomic Research Centre at Harwell, and to Blenheim Palace, where a large part of the British intelligence service had been relocated at the start of the war.

Ursula Beurton was able to ensure that a substantial number of the parachuted OSS agents would be reliable communists, able and willing to make inside intelligence from the "Third Reich" available not merely to the US military in Washington, but also to Moscow.

It was, indeed, her brother Jürgen Kuczynski, an internationally respected economist, who originally recruited Fuchs to spy for the Soviets at the end of 1942.

Her visitors were unaware of or unconcerned by her periodic, and apparently casual, meetings with Fuchs[14] in Nethercote, Banbury or on country cycle rides.

Ursula Beurton returned to East Berlin, in what had been the Soviet occupation zone and was now becoming the German Democratic Republic, in October 1949.

Reportage aus Prag über die Tätigkeit unserer Ingenieure im Ausland" was published under the name "Ursula Beurton" in Berlin in 1956.

On 10 November 1989, immediately after The Wall was breached, she addressed tens of thousands of people at a meeting in the Berlin Lustgarten (pleasure park) on the subject of her faith in Socialism with a human face.

[24] During the run-up to German reunification, she placed great faith in Egon Krenz, who briefly led East Germany.

[7] (Es war nicht immer leicht zwischen Fehlern ehrlicher Genossen und Taten des imperialistischen Gegners zu unterscheiden.

Bei so vielen Schuldigen konnte es schon geschehen, dass auch Unschuldige mitbetroffen waren.

Aber es macht sich eine gewisse Hoffnungslosigkeit breit, wie ich sie vorher noch nie gehabt habe.

In the opinion of one historian who has studied her career, she was "one of the top spies ever produced by the Soviet Union and her penetration of Britain's secrets and MI5 possibly went far deeper than was thought at the time she was operational".

[28][29] Werner herself could be more reticent about her contribution: "I was simply working as a messenger" ("Ich arbeitete ja bloß als Kurier".

)[7] What is incontrovertible is that she engaged in an exceptionally high-risk trade on behalf of Stalin's Intelligence machine without being shot by the enemy or sent to the Gulag by her own side.

Sandór Radó with whom she had worked so closely in the hills above Geneva also spent long years as a guest of the Russian Gulag.

[7] As far as her story has come into the public domain, Werner suffered nothing more harrowing than a couple of pointed but ultimately inconclusive meetings with British Intelligence agents in 1947.