Madonna, 42, announced yesterday that she will perform her first British concert in seven years at a by-invitation-only gig to be held Nov. 28 at London’s Brixton Academy. “This is a chance to get my feet wet on stage again and a way to say thank you to an intimate group of fans for all their support over the years,” the Material Mom said in the announcement broadcast by the BBC. “It’s a party that 3,500 people are invited to — and I am going to sing a few songs at my party.” Richard Ashcroft and Texas will be her supporting acts, according to the BBC. Madonna, who shares a London residence with movie director (and father of her 3-month-old son, Rocco) Guy Ritchie, delivered a brief, five-song concert at New York’s Roseland Ballroom last Sunday. This morning, gossip columnist Liz Smith reports that Madonna wore two Britney Spears T-shirts on Sunday, one at the Roseland gig and another during the party afterwards. Smith reports that Madonna has a maternal concern for the youthful Spears, who, Madonna fears, is the object of obsessive media coverage.