Sparks, The Forum, London <!-- none onestar twostar threestar fourstar fivestar -->

More than three decades after their child-scaring Top of the Pops debut with "This Town Ain't Big Enough For Both Of Us", Sparks remain one of the oddest and most inventive pop groups in the history of popular music. And the oddball double act of Ron and Russell Mael remain two of the unlikeliest pop stars ever.

Russell, the singer, remains lean and trim and fit enough at 53 to throw rock-star poses; older brother Ron, the keyboard player and songwriter, is still weird and scary in his 1940s bank-clerk outfit, with Brilliantined hair, pencil moustache and geeky specs.

Sparks' music has changed beyond recognition. Never content to stick to a winning formula, the duo have dabbled in art-rock, glam pop, electro disco, big-band swing, military marching music and operetta without losing their own distinctive identity.

Today, the Maels are at a creative peak, driven by an urge to make unique music. A listen to their latest album, Hello Young Lovers - performed here in its entirety in the first hour of this show - demonstrates that in this they have succeeded. An adjective-defying blend of classical strings, chorale, hard rock and satirical lyrics, it has been adapted into an extraordinary theatrical live experience. Blending film, animation and comic vignettes, the music gains an extra dimension to fit the scale of its ambition.

The supporting musicians double up as choristers to echo Russell's vocals on the opening "Dick Around" before tending to their instruments. Built on a blend of classical string samples, rock guitar riffs and drums, it's a mesmerizing modern take on operetta, its cryptic lyrics recited in trance-like repetition by Russell's falsetto.

The visuals play up to Ron's deadpan humour as he shoots glances at his animated alter-ego on the big screen, has a cartoon-style punch-up with himself and indulges in some comical axe-hero histrionics.

After an interval, Sparks revert to a five-piece rock set-up and give the audience all the old hits. By the time they get round to "This Town Ain't Big Enough For Both Of Us" and "Amateur Hour" the whole place is dancing and singing along like it's 1974 all over again.