Security group G4S appeared to bounce back from its Olympic contract shambles with a rise in revenues but the company admitted there was still work to be done to rebuild its reputation.

The company said revenues rose 4.1pc in the first nine months of the year, or 6.9pc including the London 2012 contract, Operating margins were lower compared with the same period last year.

The update from G4S was welcomed by the City and shares rose 3.5pc to 270p. However, contracts to run nine British prisons to be awarded this week will be a key test of whether the Government is willing to forgive its Olympics mishap and farm out new contracts to the company.