[Tom]

Actors probably are used but not in the sense you think. The same people do the rounds on reality programmes and other programmes. Examples include Sasha: Beauty Queen at 11's mum was on Wife Swap, the same contestants have been on both Deal or no Deal and Goldenballs, a woman who did Holiday Showdown popped up in Sugar Rush and Mario & Lisa from BB9 have been on practically every programme going. Don't be surprised if you've seen them before on something similar, the chances are you probably have.