They began with a whimper, rather than a bang. Bronx bassist William Parker was still tuning up when Zhenya Strigalev, Russian by birth but a regular performer at this south London restaurant and vodka bar, summoned the first quiet squeak from his alto saxophone. Parker’s playing became gradually more deliberate, but it was hard to say exactly at what point the London Jazz Festival gig had officially begun until Parker’s co-leader, the Louisiana-via-Chicago drummer Hamid Drake, finally picked up his mallets.