I was at the GVF / Second Sons gig at the O2 Academy in Islington last night. Both bands performed brilliantly, and elicited a great response from the packed audience. GVF in particular received a rapturous response throughout. As @Thunderpaws says about Glasgow, the audience demographic in London was a complete mix - males & females from late teens through to your mature rock fans, and all points in between.
Sam Kiszka's bass (and keyboard) playing was most excellent, Josh's vocals were pretty close to album quality and I do like his style, although it was impossible to understand his rambles between songs. I found Jake's guitar playing perhaps a bit limited during their longer wig-out sections on a few of the songs, but otherwise he was good. I wouldn't be surprised if they sell out the Hammersmith Odeon (or whatever it's now called) by the time they return to UK shores.