Deep Purple, Excel, London

When Ritchie Blackmore left Deep Purple for the second time in 1993, many predicted the end of the group who put the classic in rock. Now the guitarist and his madrigals have fallen so far off the radar he only registers the odd play on Radio 2, while his former bandmates have been wowing audiences all over Europe this summer.

As they open with a triple whammy of "Fireball", "Into the Fire" and "Strange Kind of Woman", from their early Seventies heyday, they certainly roll back the years, even in a nondescript open space at the British International Motor Show Music Festival. Playing in front of a broader than expected audience, including couples in their forties, their teenage sons, and City gents in pinstripe suits and ties, Purple look like they're enjoying themselves.

Arms aloft, tanned vocalist Ian Gillan makes like a bird as the band takes off, much like a plane from neighbouring London City Airport does later on. They even dig out "Mary Long", a pop at Mary Whitehouse from Who Do We Think We Are?, the 1973 album when the rot set in for what rock family tree spotters always call the Mark II line-up. The current Purple is as close as you're likely to get to this design classic. The well-oiled engine room still features bandana-wearing Roger Glover, he of the pinging bass, and walloping drummer Ian Paice. Keyboard-player Don Airey keeps the rumbling Hammond organ foundation solid, and endears himself to the locals with "Maybe It's Because I'm a Londoner" during his solo spot. Guitarist Steve Morse has been with the band for 15 years and bends the strings like Jeff Beck. It's fair to say no one, not even the most hardcore fan, misses Blackmore.

The years haven't been kind to the risible lyrics of "Space Truckin'", though the car-referencing "Highway Star" – "It's a killing machine" – goes down a storm in this setting. Everyone films the closing "Smoke on the Water" on their mobile phones, testimony to the song's hold on the average rock fan's psyche 36 years on. As the encore drifts from "Black Night" into Canned Heat's "On the Road Again", it's obvious that Purple are comfortable with their hardest-working, hardest-rocking band status.