It is understood Mark Hamilton, a former bodyguard to Beatles star Sir Paul McCartney and the man who led G4S’s Olympics team, left the world’s biggest security firm by mutual consent.
Chief operating officer David Taylor-Smith and global events director Ian Horseman Sewell resigned in September after an internal review into the contract, while chief executive Nick Buckles held onto his job.
G4S was due to provide 10,400 staff for the 2012 Olympics, but said two weeks before the event it could not provide enough staff, requiring 4,700 military staff to step in and make up the shortfall.
Last week it was announced that G4S had lost its contract to run Wolds prison, and had failed to make the shortlist for several other jails.
G4S last week posted 6.3 per cent revenue growth over the nine months to September, yet it said the US government market and European pipeline would remain challenging.