It's one of those moments every actor dreads. All that rehearsing, all that learning of lines... but you suddenly can't think what you're supposed to say next.
Picture, then, Tony Haygarth - an acclaimed Shakespearian actor and veteran of everything from Boys From The Blackstuff to Clockwise and Midsomer Murders - who found himself lost for words (or at least, lost for the right words) a few minutes into his performance as Alfred Doolittle in Pygmalion at the Theatre Royal in Plymouth.
It's a tough role for any actor, and possibly the most demanding in Shaw's play, calling as it does for flights of articulacy that would have impressed any real-life Professor Higgins as much as it did the audience for Peter Hall's touring production.
Sitting with his back to the wings, Tony stuttered, then spluttered, and without missing a beat, announced, in character: "Could somebody please give me a line?"
At which point a prompter in the wings shouted out the line that had eluded him, the audience erupted with cheers and applause at his masterful recovery from what could have been an embarrassing situation, and the play continued as intended.
I've very occasionally seen professional actors forget their lines on stage - but never, ever, have I seen an actor deal with it with such aplomb.
It takes a brave actor to invent an extra line for a George Bernard Shaw play, but I couldn't help feeling that Shaw himself, had he been there, would surely have shared our utter admiration for Tony Haygarth's imaginative handling of every actor's nightmare.
Leaving the Stage Door afterwards, Tony confided that it was just one of those things and he was glad the audience appreciated the way he'd solved the problem.
Actors don't get much more professional than that.
If you get a chance to catch his performance elsewhere on the tour, treat yourself. I can't imagine he'd forget that particular line again, but the way he delivered the rest of them was something to behold - and certainly worth the £19 a ticket, as he stole the show whenever he appeared.
Jon McKnight
Author of Sort The Bastards!