The one rogue contract defence?

Speaking to BBC News earlier, Policing Minister Nick Herbert said of the G4S Olympics shambles:

“I think people can see perfectly clearly that this was a one-off event.”

What would you call that line of defence? We’ve had one rogue journalist.

Is this just “one rogue contract”?

He also suggested that G4S’s failure did not affect other contracts by the company.

They’ve embarrassed the country.

They’ve caused troops to be drafted in to save the Olympics.

What on earth would the have to do to lose such contracts exactly?