Dr Jacob Bronowski and editor Cyril Connolly were among those whose political views were suspected by the secret services

This article is more than 9 years old

This article is more than 9 years old

MI5 bugged the phones of leftwing journalists and writers in an intensive but unsuccessful attempt to discover more about the Cambridge spy ring, according to newly released, hitherto top-secret files.

It also drew up voluminous reports on scientist Dr Jacob Bronowski, who became a popular broadcaster, in surveillance operations described by his daughter as "shocking ... just like a Stasi file".

Files released by the National Archives include transcripts from phonetaps from the London flat of journalist and author Philip Toynbee, made shortly after his friend Donald Maclean fled to Moscow with Guy Burgess, a fellow member of the notorious Cambridge spy ring.

The files, from the early 1950s, suggest MI5 was mainly interested in Cyril Connolly, editor of the literary magazine Horizon, who lived in Toynbee's Paddington flat at the time.

MI5 recorded conversations in which poet Stephen Spender, publisher George (later Lord) Weidenfeld, poet WH Auden, painter Lucian Freud and philosopher Sir Isaiah Berlin were all talked about.

MI5 was most keen to discover what Connolly and his friends knew about Burgess and Maclean.

It carefully annotated newspaper articles that Connolly had written about his former acquaintances.

The files show that MI5 identified the art historian Anthony Blunt and journalist and academic Goronwy Rees as being among Burgess's friends in October 1952, 12 years before Blunt confessed to spying for the Russians.

"We are, for your own information, still making active enquiries in the Burgess circle, which, of course, included Rees, Blunt and many others," an MI5 officer wrote to the British embassy in Washington.

He added: "We do not wish to encourage the FBI to direct a lot of questions at us about our progress in this peculiarly British field of counter-espionage."

Although Blunt, the official surveyor of the Queen's pictures, confessed in 1964, a hugely embarrassed establishment covered the matter up until he was exposed in a deathbed tipoff from Rees in 1979.

The FBI was particularly interested in the Cambridge spy ring, as both Burgess and Maclean had worked at the UK's Washington embassy.

The papers show how MI5 built up a large file on Bronowski, a mathematician and scientist who became a successful broadcaster and household name through his 1970s BBC documentary series, The Ascent of Man. He first came to MI5's notice in October 1939 when a "casual informant" in Hull, where Bronowski was a university lecturer, claimed he held "extreme left and anti-British opinions".

A year later, a Hull police officer told MI5: "I am well acquainted with the members of the local Communist party and at no time have I ever known him to be associated with them."

A series of subsequent police reports warned MI5 that Bronowski had spoken at a Left Book Club meeting about the "alarming growth of fascism". One report described him as a "skilful speaker and agitator of the 'communist intellectual' type", another as a "red intellectual". Yet another misinterpreted a satirical poem.

But his mathematical talents and expertise on the impact of bombing led the government to give him, in 1943, a job in the research and experiments department of the Ministry of Home Security.

He was later appointed a member of an official investigation into the effects of the atom bomb dropped on Hiroshima.

The files show the BBC told MI5 it had "abandoned" a series of planned broadcasts by Bronowski on atomic power.

His daughter, Professor Lisa Jardine, director of the Centre for Editing Lives and Letters at Queen Mary, University of London, told the Guardian: "I can't tell you how shocking it is for me ... It's just like a Stasi file. It's scary." Members of his family were Communist party members, but her father "took the decision very early on never to have an official association with politics", she said.

He turned down the offer of a post in Harold Wilson's Labour government and later emigrated to the US, because he could not get a senior post in Britain, Jardine said. But he never suspected that MI5 had a file on him.Harmonica player Larry Adler, who performed with Elton John and Sting, was investigated by MI5 over concerns about his alleged communist sympathies, the files confirm.

US-born Adler moved to Britain after being labelled a communist and blacklisted in America, but the files make it clear that MI5 did not consider him a subversive, the files make clear.

Nazis' nasty surprises

German spies were supplied with poisoned products – including chocolate, sugar, pills that looked like aspirin and doctored Nescafé – as well as cigarette lighters that gave off lethal fumes when ignited, to kill prominent individuals among the allies after the Nazis' defeat in the second world war, the MI5 files reveal. Female agents were supplied with "microbe" weapons hidden in handbag mirrors.

The Nazi leadership also planned to plant sleeper agents around the world after the war to provoke global unrest and create a "Fourth Reich", the files disclose.

Olivier Mordrelle, a leader of a separatist nationalist movement in Brittany, told his interrogators after he was captured that "ample funds" had been transferred to South America and "trustworthy key men" had been sent to live in Spain and Switzerland.

Mordrelle said he attended a meeting in Deisenhofen, near Munich, in April 1945 at which German postwar resistance plans were discussed.

He said he was told by a senior SS officer that underground agents were to lie low after the war ended until they were told to organise anti-Bolshevik movements in their countries in order to "stir up unrest culminating in civil war".

The allies also set up a secret network of agents and arms dumps, called Gladio, in the event of communist-led uprisings in western Europe, it has already been revealed.