It takes a truly great performance to lie to your friends

One of the nicest things about life as an actor is that occasionally you offer up a performance that surprises even yourself. It's a rare phenomenon. Most of the time we trot out the same stereotypical portrayals for the same stereotypical productions - a policemen here, a doctor there, a distraught husband here. Most acting is, after all, just entertainment. Viewers don't want to know about the inner yearnings of my traffic cop who only has five lines.

Whether he's unhappily married or has always harboured a secret desire to run off and join the circus, they just want to know whether I arrest the villain or get coshed over the head. But last week I gave a performance of such skill and daring that I rate it among my very best. What's more, I managed it with no rehearsal. I'm just sorry it was for one night only. The occasion was the immediate aftermath of a play I'd attended in London's West End. My old mate Stephen is in the cast, and he'd left me several messages expressing the hope I'd go along and see the production. Which inevitably meant seeing him backstage after curtain down. In theatrical parlance, I was going to have to "go round".

"Going round" is a diplomatic minefield for all actors. It's obligatory procedure to pay your subsequent respects if you have acquaintances in the show, and as long as you've had a genuinely enjoyable time it's a relatively painless interlude - you tell them how marvellous they were, they modestly accept your benediction, and everyone's happy. But what if the production - or worse, your friend's performance in it - is a stinker? How truthful should you be afterwards? Do you tell the truth and risk ruining a beautiful friendship, lie through your teeth, or adopt a middle way, accentuating the positives but pointing out one or two areas in which the production could be made "even better"?

It's a no brainer. Actors require one thing and one thing only while the show is running: to be told, "You were wonderful, darling." Nothing less will suffice, not until the production has closed for good. Then we can talk again. But in Stephen's case there shouldn't have been a problem. After all, the show had garnered fabulous notices, with one reviewer even going on to call it "a life-changing experience, reminding us of everything that's good about British Theatre".

Yet it was soon obvious from my seat in the stalls that the critic must have been on medication. The play - and Stephen's performance in it - was unbearable: turgid, melodramatic, lachrymose, the sort of evening that makes you want to pour paraffin over your head and set a light to it. With the best seats in London's theatres nowadays costing up to $120 (Dh440) a pop, merely purchasing the ticket in the first place had nearly reduced me to tears. As I sat in the darkness of the stalls I found myself churning over in my mind all the other things I could have spent my precious money on: a new jacket, a bottle of decent after-shave, or a day-trip to Paris on Eurostar. With each realisation, I sunk deeper into gloom.

As I plodded glumly round to the stage door afterwards, I weighed my options. On the one hand, every scintilla of my actor's instinct told me that sugared words and honeyed lies were essential, if only to give Stephen the confidence to go on again the following night. But he and I have known each other most of our adult lives - I'm the godfather of his two kids for goodness sake - if I couldn't speak the truth to him of all people, then what did it say about our friendship?

He'd appreciate hearing my real sentiments, of that I was sure. He'd only respect me all the more because of my candour. Decision made, I felt a weight had been lifted from my shoulders. To my horror he was already waiting for me outside the stage door. "Well?" He beamed. "What did you think? Terrific isn't it? Be honest!" My resolve melted away faster than an interval ice cream in a heat wave. "Yes," I replied, conjuring up a look of bedazzled awe in my bloodshot eyes. "It was extraordinary. Truly exceptional."

An hour later as we parted and I thanked him for the umpteenth time for my life-changing evening, he returned the compliment by enfolding me in a rib-crunching hug. "Thanks for coming," he said huskily. "I knew you'd love it. You're a real pal." Somehow I'd managed the delicate manoeuvre of both gritting my teeth and lying through them at the same time. It had been one of my toughest roles, but I'd gotten through it - apparently to universal acclaim.

Michael Simkins is an actor and writer based in London