THE BBC allowed MI5 to vet staff right up until the 1990s, it has been revealed. Files detailing the broadcaster’s secret links to the security services show that investigations were made into the lives and allegiances of thousands of employees, including reporters, newsreaders and continuity announcers.

“Subversive” political activity led to appointments and promotions being blocked by the corporation, which held a blacklist of organisations.

A memo from the 1980s show these included the Socialist Workers’ Party, the Communist Party, Militant Tendency and the Workers’ Revolutionary Party as well as the National Front and the British National Party.

Journalist Isabel Hilton was refused a job in 1976 with BBC Scotland because, she thinks, she knew a member of the Communist Party at Edinburgh University, a fellow member of the university’s China-Scotland organisation.

“I still feel indignant,” she said. “I felt it was a squalid way to behave and I still do.

“More seriously, beyond the particulars of my own case, I felt that the BBC had betrayed public trust by promoting a system in the UK by which the secret police were licensing and blacklisting journalists.

‘‘Whenever I hear the BBC boasting about its fine traditions of journalism, I feel a minor stab of outrage.”

MI5 evidence was particularly rife in the late 1970s and early 1980s just as millions of viewers were enjoying the fictional adventures of fictional spy George Smiley in Smiley’s People and Tinker, Tailor, Soldier Spy.

Well-known faces such as Anna Ford, John Humphries and David Dimbleby all started their careers with the BBC when the vetting was taking place.

Ironically, however, it failed to weed out real-life spy Guy Burgess who worked for the BBC during the Second World War.

The vetting files, which have been studied by journalist Paul Reynolds, also show attempts by BBC figures to cover up its links to surveillance despite repeated questions from the press and trade unions.

One file note, dated March 1, 1985, states: “Keep head down and stonewall all questions.”

The BBC denied vetting was taking place for decades but it began as early as 1933 when both MI5 and the BBC agreed the broadcaster was in need of “assistance in regard to communist activities”.

In 1985 The Observer exposed some of the political vetting at which point it began to be wound down but even then some staff were kept on the vetting list on the pretext they had access to restricted government information.

The BBC has refused to reveal if any staff are still vetted.

“We do not comment on security issues,” said a spokesperson.