Bettany was recruited by the Security Service (MI5) in 1982 at a time when the service was coming under increasing pressure to recruit more staff from the 'working classes'. His unsuitability quickly became apparent when on one occasion after he had been working for MI5 for only a brief period, police stopped Bettany after he had staggered onto a train, heavily under the influence of alcohol, offering no ticket and attempting to evade the guard who had to chase him down the aisle of a coach. He shouted: "You can't arrest me. I'm a spy!" to police officers. Irrespective of this incident and many others like it, MI5 kept him on its payroll. He was then, inexplicably, promoted to the Russian desk, even though he had little or no background or knowledge qualifying him for that appointment. In his new position, Bettany had access to information that identified all known KGB agents in England. Bettany made copies of secret documents and then attempted to make contact with the KGB.
Ironically, it was the KGB itself that informed MI5 of Bettanys treachery believing that they were being 'set-up' by the Security Service. The Soviet intelligence service lost a potentially priceless contact within MI5 who could have identified which of their agents and operations were compromised. For Bettany had top secret clearance and the information to which he had access was so sensitive that even the Attorney General Sir Michael Haver's, who was to prosecute Bettany in court, was apparently prevented from fully reviewing the information.
Bettany, tried 'in camera' claimed innocence but was convicted of ten charges dealing with violations of the Official Secrets Act. Lord Chief Justice Lord Lane in sentencing Bettany said "You have made treachery your course of action. It is quite plain to me that in many ways you are puerile. It is also clear to me that you are both opinionated and dangerous. You would not have hesitated to disclose names to the Russians, which almost certainly would have led to death for more than one person." Bettany was sentenced to twenty-three years in prison. The case, along with other recent breaches of British intelligence, including that of Geoffrey Prime who had worked at GCHQ at Cheltenham, so alarmed the CIA that it demanded that MI5 take immediate steps to improve its chronic lack of internal security precautions.
However, Bettany still had another chance to betray his country for while on remand in Wandsworth prison in late 1984 Bettany befriended Pat Magee, the Brighton bomber who had been arrested and charged with bombing the Tory Party conference. Bettany revealed to the IRA killer that there was a British spy close to Martin McGuinness in Londonderry, Willie Carlin, who had been recruited by MI5 in 1974 while a soldier in the Queen's Royal Irish Hussars and spent 11 years undetected by the IRA. His main role had been to report on McGuinness's political development and encourage him and others to abandon their military campaigns for a political solution. Republicans after a prison visit quickly relayed the information to McGuinness, who ordered an investigation into Carlin. Other informants inside the Provisional IRA told the spy's handlers that his cover had been blown and Carlin's covert career came to an abrupt end. On 3 March 1985, the Army spirited Carlin and his family to England
The key IRA informer, in hiding for 16 years, risked his life in 2001 to give evidence to the Saville inquiry investigating the killing of unarmed Catholics in Londonderry on 'Bloody Sunday' in January 1972. He was to confirm that the former IRA commander Martin McGuinness did not fire any shots on the day of the fateful civil rights march that ended in the deaths of 14 civilians.
