If Sinn Fein is correct to claim that Gerry Adams' former driver and bodyguard, Roy McShane, was working as a British agent, then almost all the key meetings and movements of the republican leader were known to the British for the past 20 years.
This would include secret meetings with the Irish Government leading up to the ceasefires.
Mr McShane was rarely far from Mr Adams' side from the time the Sinn Fein leader entered the public arena in the mid-Eighties.
It would also mean that at least two figures who acted as Mr Adams' closest personal aides, Mr McShane and Denis Donaldson, were reporting back to their handlers.
It is believed both were among the small army of double agents inside the IRA recruited by the RUC Special Branch from the 1980s onwards, under the direction of former Special Branch boss and subsequent RUC Chief Constable, Ronnie Flanagan.
Mr Flanagan's officers infiltrated republican and loyalist terror groups to an extent that is only now becoming apparent.
All the agents recruited by the RUC Special Branch were handed over to the British domestic intelligence agency MI5 as part of the policing deal leading up to the 2006 political settlement between Sinn Fein and the DUP. MI5 now handles "political" intelligence gathering, leaving "ordinary" policing to the PSNI.
MI5's main target now is the dissident, ex-Provisional IRA members who are threatening to began a campaign of assassinations and attacks on shops and commercial premises.
Mr McShane's alleged role as an agent was made public on Friday by Sinn Fein, who claimed he had said his goodbyes to his family in west Belfast and had been taken into protective custody -- presumably by his MI5 handlers.
Sinn Fein's Alex Maskey said Mr McShane had nothing to fear from republicans. "Let's face it, the war is over."
Suspicion appears to have fallen on Mr McShane, 58, and some of the other drivers from top Sinn Fein figures two or three years ago. In September 2004, a number of bugging devices were discovered at Sinn Fein's head offices on the Falls Road in Belfast and in a car used by Mr Adams.
It is believed that there was a "security audit" and Mr McShane and a number of others were moved away from driving and body guard duties. In the past 18 months, Sinn Fein said that Mr McShane had been driving a taxi in west Belfast.
As well as Denis Donaldson, who was shot dead at his holiday home in Donegal in April 2006, other figures who have at times been part of Mr Adams' inner circle included former "internal security" boss, Freddie Scappaticci, who was also exposed as an RUC mole in 2003.
Republican sources in Belfast yesterday claimed that Mr McShane and Mr Scappaticci were close friends.