Opik, who recently thanked this organ for reminding him to declare some work for lobbyists Luther Pendragon, was playing harmonica for 'The Aviators' - the band of politicians who formed for one night only.
Alongside him was Tory MP Anne Milton, Labour's Ian Cawsey and Peter Wishart of the SNP. With no Cheeky Girls in sight, punters had to make do with Labour MP Emily Thornberry on vocals.
Unity had organised the event for Friends of the Earth as part of its campaign to include aviation in the Climate Change Bill.
The unlikely quintet eventually gave way to a real band - Razorlight - but only after Opik had committed the most rock and roll act of the night by kicking over the amps and throwing a TV out of the window. Or maybe not.