I only went there once, when I was rehearsing nearby with a band based in Acton - we'd all pile into a van and drive through the centre of London to use a downmarket rehearsal studio in Wapping, so I had to pop in - and popped out with a new Trace Elliot combo. I can't remember the type now, but it was a 4 x 10 and bloody heavy. I lived on the third floor of flats in Acton then, and there was no lift, so I had to carry the damn thing up and down the stairs all the time. Sounded great, though!
Pretty sure the Bass Centre was up some stairs then, or maybe just the amps were. Would have been about 1983/5, somewhere around then, anyway.