“Fuck yeah!” grins Paul Banks. Interpol have just played a blistering rendition of PDA — greeted with riotous bouncing, moshing, and a persistent crowd surfer upfront — to end the main set of a thrilling Roundhouse gig. It’s a show that almost never happened. Yesterday, only 45 minutes before the venue doors were set to open, the band tweeted: “Due to illness, we sadly have to cancel tonight’s show—it is our intention that tomorrow’s show will go ahead—we greatly apologize for the late nature of this announcement.”