According to the Irish Star Brian and Rog were recording in Dublin (presumably the 'We Will Rock You' mix to be used at the Brits, but this wasn't stated).

Apparently they met Mel C who was in town and ended up in an impromptu session along with Bono
at his studio.

They were also joined by a band called Crush who are an Irish band that Brian and Roger jammed with after
meeting them in a Dublin pub.