Björk, Hammersmith Apollo, London<br />Method Man and Redman, Shepherds Bush Empire, London

Spirit of a child in the hands of a maverick

There may come a day when Björk Gudmundsdottir sits back, accepts the plaudits, and settles into being a national treasure. But I wouldn't hold your breath.

The truth – instantly emphasised the moment she steps on stage in a pom-pommed headdress and what looks like a giant sweet wrapper – is that Björk is still too mercurial to be a monolith, too interesting to be a diva, too restless to be a legend. It's for the best.

At the age of 42, she retains the mentality of a child in the best possible sense (inquisitive, exploratory, daring), and, viewed in a certain light, her inconsistency is a strength: every few years she'll surprise us by throwing out an album as stunning as Vespertine or Volta (for which this is a promotional tour).

Against a backdrop which seems to echo her musical mix of the twee (flags printed with cutesy fish and frogs) and the ultra-modern (expensive-looking computer screens), and assisted by an ensemble which includes an all-female brass band from Iceland, she plays a Volta-heavy set which takes in some of her biggest hits ("Hyperballad", a floor-shaking "Army of Me"), but nothing from her classic, er, debut, Debut.

The unquestionable high point, however, is when she is joined on "The Dull Flame of Desire" by Antony Hegarty of The Johnsons.

She ends with "Declaration of Independence", the song that controversially contributed to the China crisis when she sang it in Shanghai and chanted "Tibet!". In London she's oddly silent. When she visits Israel, one hopes she'll find her tongue.

Last time I saw Method Man face to face, he told me: "You have to understand the black man is God." A lot of water has flowed under the Verrazano-Narrows Bridge since then. This time, he wants us to buy his new CD. Sitting in a darkened tour bus in Kentish Town in 1993, I listened as the metallic-mouthed Method Man and his colleagues outlined their strange hybrid of black nationalism and Shaolin mysticism.

I'd come across the then-unknown Wu-Tang Clan on a trip to the US and understood that their minimal, cinematic hardcore sound was truly groundbreaking. Before long, we discovered the strengths of the individual Wu members, and everyone had their favourite spin-off. The first to break loose was Method Man with Tical. What we learned about Method Man was that, if you looked past that belligerent growl (nobody goes rrrah!!! quite like Meth), he is, as his name implies, a rhyme technician.

He's also, in start contrast to some of his sidekicks (notably Ol' Dirty Bastard, rest his lazy soul), that rare thing: a rapper who can be bothered to kick it live. Which is why his hook-up with the fast, fluid Redman works so well.

Method Man, aka Johnny Blaze aka The Ticallion Stallion, and Redman aka Reggie Noble aka The Funk Doctor Spock, are a long-running buddy act who even had their own sitcom in 2004. They're here to promote Blackout 2, the long-overdue successor to their 1999 duo album, but there's plenty of time for the rest of their back-cat. Method's theme tune "M.E.T.H.O.D. Man", his solo anthem "Bring the Pain" and the exhilarating "Wu-Tang Clan Ain't Nuthing ta F' Wit", in particular, raise the roof.

They're a mismatched couple in some ways. Method Man is big on bling. Redman, by contrast, wears a sweaty grey hoodie, nerdy shades and a cheap bandanna. What they both have is energy and charisma.

They barely need more than a plank's width of the stage, almost permanently tipping over the white line. Until, that is, Redman attempts a speaker-dive and Method, not to be outdone, attempts his famed crowd walk. The crowd, however, isn't expecting it, and the Wu man falls to the floor. "Pick him up! Pick him up!" orders a concerned Redman on the mic. He needn't have worried. Meth scales the barrier and, with a rrrah!!!, he's back.