Tommy Cooper, for people of a certain age, was simply the funniest ITV television performer of his generation. Over four decades, his act of bathetic one-liners, disastrously-failing magic tricks and a trademark harrumph of “Jus’ like that!” — all addressed directly to the theatre audience or camera lens — was a direct challenge not to laugh out loud. His red fez and lumbering stature made him instantly recognisable.

So what chance was there last Wednesday of actor Clive Mantle pulling off a successful portrayal of Cooper? To the gurgling delight of the Playhouse audience, he was really good. For what is effectively a one-man show, Mantle’s script is provided by John Fisher (a former TV executive who has become an acknowledged authority of showbiz variety and has written a biography of Cooper, which helps a lot). The actor has the look of Tommy Cooper just about perfectly, and the voice is 90 per cent there as well.

Mantle, who was an Olivier best newcomer award winner and played Little John in the 1980s television show Robin of Sherwood, works hard and — importantly — can also do sleight-of-hand magic impressively badly (which means, of course, that in reality, he has to be good at it).

The important element of the production, however, comes in the second half, when we go backstage and see the character in his dressing room during the interval of his show. As he takes deep draughts of gin straight from the bottle, we see the inevitably tortured clown behind the mask — the self laceration is moving — and dealt with movingly by his assistant (Carla Mendonça). Does he win this internal battle? Yes, it seems that each victory entailed loathing in nightly allowances to permit Tommy Cooper to be the performer he was, and Mantle was hugely effective in this double-role.