Flight of the Conchords, Hammersmith Apollo, London

The return of the musical comedy act Flight of the Conchords to the UK after five years has been described as a much-needed respite to the "outrageous politicking" of the post-general election period. Perhaps, more positively, one might suggest that, like our coalition leaders, the Conchords are two hopeful young men who also once had a big idea. In the Conchords' case, their idea has grown from performing it in small rooms in their native New Zealand, and at the Edinburgh Fringe, to having it turned into a cult HBO comedy series and into best-selling albums and tours.

Whether Messrs Clegg and Cameron will make beautiful music together in politics remains to be seen, but Bret McKenzie and Jemaine Clement have, without doubt, topped the musical comedy poll to levels only previously witnessed with Spinal Tap. With their often well-honed musical pastiches, the Conchords have the best of both worlds in terms of putting on part-pop concert, part-comedy shows – and therefore can tap into energy denied to most stand-ups. That said, only a handful of tunes stand out tonight as truly memorable after what is a marathon show.

Like their in-between song banter the Conchords' musical stylings are subtle, gentle comedy, all set to a largely acoustic soundtrack. Among the Conchords barnstormers are the self-explanatory homage "Bowie", that makes particular reference to "Space Oddity" ("Is it cold out in space Bowie?/ You can borrow my jumper if you like Bowie"), and "Inner City Pressure", the shameless riff on The Pet Shop Boys' seminal "West End Girls" ("You know you're not in high finance/ considering second hand underpants"). Meanwhile, the unplugged back catalogue that generally does not ape a song or band quite so slavishly includes "The Most Beautiful Girl in The Room" and the Belle and Sebastian-esque "Ex-Girlfriends" ("You could've mentioned you were a she-male in your first email").

The collection of anthems and whimsy is brought to a close with a salvo of songs that distil the essence of the gig like a highlights package. It includes slower-paced songs (in this case "Bus Driver's Song"), high-energy numbers, like the mock R&B tune "Sugarlumps", and a song that weaves in all their previous, and deliberately mundane, anecdotes about being on tour and thereby gives them a much-needed raison d'être – a long time to wait for a payoff, though. As with The Mighty Boosh, the charm of the two performers goes a long way to winning the audience round, keeping their interest until they are rewarded with a deft touch amidst the sometimes slight build up.

It's doubtful that the fans tonight, who include parents and their young children, will worry too much that the gig is overlong as most are too busy guessing what the next song is from the first couple of bars played. The Conchords will only re-inforce their status with this show even if it could have been cut into a much tighter "greatest hits" package.

Touring to 25 May ( Flightoftheconchords.co.nz)