Former director of GCHQ

Born: June 13, 1927;

Died: May 21, 2017

SIR Peter Marychurch, who has died of cancer aged 89, was a career British counter-espionage officer who served as director of the Government Communications Headquarters (GCHQ), the Government's "eavesdropping centre," during the latter years of the Cold War. That made him one of the UK's most influential "spooks" during the 1980s, providing intelligence to both MI5 and MI6.

As GCHQ Director, Sir Peter also held the rank of Permanent Secretary in the Foreign Office. His career speciality was acutely sensitive signals intelligence, the monitoring, interception and interpretation of military radio, radar and satellite signals – in his era mainly from the Soviet bloc.

One of his proudest achievements was seeing the fall of the Berlin Wall in 1989, shortly before he stood down as director and retired to enjoy his love of music . Earlier in his career, on secondment from GCHQ, he also worked for a time within the US National Security Agency (NSA), liaising between the two sides of the transatlantic "special relationship". He also had a spell as senior GCHQ officer in Melbourne, assisting Australian intelligence at the Defence Signals Directorate.

In Scotland, Sir Peter was perhaps best-known as the man who effectively ordered the dramatic Special Branch police raid on the BBC's Glasgow offices on Queen Margaret Drive in January 1987. The Metropolitan police at the same time raided the London home of Glasgow-born investigative journalist Duncan Campbell while Strathclyde Police searched the Glasgow homes of his research team. They had been working on a six-part BBC series Secret Society, exposing alleged irregularities in the UK government and intelligence agencies. The Government cited potential breaches of the Official Secret Act but critics, including Scottish Labour MP Tam Dalyell in a Commons question, billed the police raids as an illegal act.

The raids and surrounding public kerfuffle became known as the Zircon Affair, since Mr Campbell had revealed plans for a top-secret Zircon signals intelligence satellite - plans later dropped due to costs. No charges were brought against Mr Campbell or his team but the apparent Big Brother tactics by Sir Peter and his GCHQ came as a stern warning to TV producers and journalists in Scotland and beyond that they were quite possibly being monitored.

Mr Campbell's episodes were eventually aired although one, about secret cabinet committees allegedly involved in denigrating the peace movement at Faslane and elsewhere, went out somewhat modified, and on Channel 4 rather than the BBC.

In his best-selling 1987 book Spycatcher, former MI5 agent Peter Wright revealed how the then plain Mr Marychurch had helped him work on interpreting Soviet broadcasts from Moscow to Soviet agents in the West.

"A young GCHQ cryptanalyst named Peter Marychurch (now the director of GCHQ) transformed my laborious handwritten classifications by processing the thousands of broadcasts on computer and applying 'cluster analysis' to isolate similarities in the traffic, which made the classifications infinitely more precise. Within a few years, this work had become one of the most important tools in Western counter espionage."

The son of bank clerk Eric Marychurch and his wife Dorothy, Peter Harvey Marychurch was born on June 13, 1927 and attended what was then known as the Lower School of Sir John Lyon in Harrow, Middlesex. He enlisted in the RAF on VJ Day - August 15, 1945. Posted to an RAF station at Stow-cum-Quay, Cambridgeshire, he was allowed to travel into Cambridge every day to study military Russian from Soviet exiles. In 1948 he was hired by GCHQ, at the time in Eastcote, Greater London, which had been an outstation of the Bletchley Park code breakers during the war.

In 1953, he was seconded to the US National Security Agency (NSA) in Washington, where he worked with the legendary American cryptologist Ann Caracristi on secret Soviet communications. In his spare time, he toured the US by car and also visited pre-Castro Cuba before returning to GCHQ in England, having become a staunch Atlanticist which he remained for the rest of his life. He also had a spell at RAF Pergamos in Cyprus (1958-60), again monitoring Soviet activity.

When appointed GCHQ director in December 1983 to replace Sir Brian Tovey, Sir Peter immediately took on a massive problem: in January 1984, a month after he took over, the Prime Minister Margaret Thatcher imposed a controversial ban on trade unions within GCHQ over security concerns. Sir Peter had supported the ban. He weathered the storm but admitted, years after he retired, that he was pleased to see the ban lifted in 1997 after a no-disruption guarantee from the unions.

During most of Sir Peter's career, the GCHQ had remained a shadowy organisation, largely under the public's radar, even though its cover had first been blown in 1976 by Time Out magazine. That article, co-written by Duncan Campbell, shocked even the spouses of GCHQ staff who had no idea what kind of work their husbands or wives were doing when they left after breakfast. In 2003, however, GCHQ "came out" in a big way by moving to the now-famous "doughnut" building outside Cheltenham, which now has a staff of more than 6,000.

After his 1989 retirement, Sir Peter indulged his passion for music, becoming chairman of the Associated Board of the Royal Schools of Music and chairman of the Cheltenham Music Festival. His name was given to the Sir Peter Marychurch award, given annually for work in international cryptology.

Sir Peter Marychurch is survived by his wife of 52 years, June (née Pareezer).

PHIL DAVISON