Lee Mack live review: Glimpses of ad-lib brilliance ★★★

It's a brave stand-up comedian whose encore is to invite questions from a crowd that has been, up until now, notably restless.

With a fair few heckles lobbed through the first hour of Lee Mack's set at the Hammersmith Apollo – part of a eight-night residency for his 'Hit the Road Mack' tour – it felt as though such an unpredictable Q&A finale could go either way.

Yet it was Mack's 20-minute riffed return to the stage that proved to be the pinnacle of the evening.

Earlier, the 46-year-old comedian had carefully – if not a little too quickly at times – delivered his well-rehearsed material on the ridiculousness of star signs, joyless holidays and family life.

His largely safe, mostly predictable topics were perfect for the middle-aged and middle-class audience, but we had been warned by the man himself almost as soon as he took to the stage that it was a new tour, with new jokes, so "it might be a bit s**t". His jokes weren't s**t, but they weren't great. Many of the set-ups and punch lines could be seen from row ZZ.

And for such an established comic, Mack appeared visibly nervous for the first 10 to 15 minutes or so of his set. Tripping over a few of his words and frantically pacing the stage, he never seemed wholly comfortable with his practiced gags.

Which is what made Mack's unscripted finale such a joy. Not Going Out has its fans, but Mack is arguably at his sharpest when appearing on panel shows, and his speedy comic timing makes him a lynchpin of Would I Lie To You?.

It was these flashes of spontaneous brilliance that the audience relished when Mack very capably dealt with questions that jibed about Tim Vine, asking how his gran was and even wanting to steal his shoes. Loosening up, Mack dropped the pacing and relished interacting with the crowd.

While rehearsed comedy is simply not Mack's strength, he is a fantastically talented ad-lib comedian. When he gives himself the chance.