when the monkey walks

Only just come across this three-minute clip from Newsnight Review, where Trevor Nunn and Kevin Spacey discuss the Old Vic's production of Inherit The Wind and the unusual business of rehearsing with a monkey. Nunn says:

We do have a monkey in the play, as is required by the writing. When the monkey gets up on its hind legs and starts to walk ... I don't mean to say there's a friendly recognition, we're not all saying, 'Hi buddy', but you do understand something.