"The British Empire's over, we've scared the ravens off," said Elvis Costello, but it was his fans whose absence was more apparent.

The failure to completely sell out the Tower of London was perhaps due to the distraction of Live Earth. It hardly mattered, though, as Costello established a formidable partnership with Allen Toussaint, the veteran New Orleans piano player.

They were performing tunes from their album of collaborations, and though Costello may not have a natural R'n'B voice they made a virtue of their contrasting styles.

While the 69-year-old Toussaint grinned away during his silky piano playing, Costello sang and strummed his guitar as if he'd had a really bad day. That was especially true during the baleful River In Reverse.

Occasionally, Costello's bark overwhelmed the more soulful songs. But the band provided some equally robust bursts of trumpet and saxophone throughout the set, which made Seventies singles such as Alison sound spectacular.

Costello clearly viewed Toussaint as the senior partner, paying tribute to his musical legacy as the older man sang A Certain Girl.

Inevitably, though, this crowd wanted more of Costello's tuneful punk classics. And during Pump It Up, middle-aged fans surged forward to dance, ignoring their lack of ability and the protesting security guards.

When a bearded Beefeater started shimmying too, though, the bouncers sensibly decided to let everyone have their fun.