Baroque 'n' roll stars: Britain's most exciting new bands - The Last Dinner Party and Picture Parlour - unite for homecoming celebrations in the capital

So perfectly formed, clever, poised, witty and confident did The Last Dinner Party appear when they gatecrashed the British music scene with the release of their genuinely breath-taking debut single Nothing Matters just six months ago, that their arrival was immediately followed by predictable whispers that they couldn't possibly be '4 Real', that they must surely be the invention of a Machiavellian industry svengali. As if the suits in the boardrooms of the UK's major record companies have ever displayed the kind of left-field imagination capable of conceptualising a group this fabulously out of step with current trends. Entirely mindful that their influences - Roxy Music, ABBA, Queen, Sparks, Siouxsie and the Banshees, classical / choral compositions - aren't exactly key components of any current pop star's core sound, in her group's very first press interview, band leader Abigail Morris archly told the NME, "We’re just five dads trapped in gorgeous young bodies."

When the band announced their debut UK headline tour in June, their October 17 show at East London's 1200-capacity EartH (Evolutionary Arts Hackney) sold out in just three hours, and all tickets for a hastily-added second show at the venue 24 hours later also disappeared within a breath. Nice work for a band who were playing to 300 fans at the Moth Club in the same borough less than a year ago, and have released just three singles to date.

Before The Last Dinner Party are crowned as homecoming queens tonight, the quickly-filling venue is treated to a fabulous amuse bouche in the form of the quintet's best mates (and Island labelmates) Picture Parlour. Fronted by Liverpudlian vocalist/guitarist Katherine Parlour and Yorkshire-born guitarist Ella Risi, the quartet released their second single, Judgement Day, just 24 hours ahead of this show, and, like their more-celebrated pals, they already sound bound for inevitable glory.

The London-based band may be a more conventional group than the baroque n' roll headliners - Risi and bassist Sian Lynch repeatedly unite centre-stage to gleefully throw shapes that wouldn't be out of place if they were playing between Wild Horses and The Members on the final day of 1979's Reading Rock festival - but in Parlour they have a world class vocalist whose timeless voice transcends the here and now. Picture Parlour are still so fresh that their leader feels compelled to politely point out that the set-closing Norwegian Wood, their debut single, isn't a Beatles cover, but the strength of songwriting displayed on Sawmill Sink Hole and the punky Neptune 66 offer proof that this is a band who won't be standing in anyone's shadow for very long.

Even when they're at their most serious - "This is a song about feminine rage" says Abigail Morris introducing Feminine Urge - The Last Dinner Party look like they're having more fun than any other five individuals on earth at this moment in time. Those who argue that music is becoming the preserve of the privileged will wince at some of the irrepressible, hugely charismastic vocalist's pronouncements - "Emily is going to play the flute on this one, so be quiet," she trills ahead of Beautiful Boy in pure convent school head girl tones -  but it's hard not to be swept along into this world of their own making, with its undertones of dark thoughts, forbidden yearnings and transcendent passions. On Your Side gets Pixies' Where Is My Mind appended as a sublime coda,  hormonally-charged new single Our Lady Of Mercy is introduced by Morris as a song inspired by Catholic school  (wherever she was educated was clearly infinitely more stimulating than my nun-heavy alma mater) and when Emily Roberts straps on a Flying V for the riotously riffy Godzilla, it's like Runaways-era Lita Ford is channelling Brian May.

So well-drilled and technically gifted are the band - Roberts and keyboardist Aurora Nischevi studied classical music at The Guildhall School of Music and Drama - that The Last Dinner Party's 14-song presentation already has the feel of a greatest hits set, but an as-yet-untitled new song featuring raucous shout outs to a "Big Dog" suggests that there are still fine-tunings being made before their debut album is committed to analogue tape or shellac 78s or perhaps perforated piano rolls. In whatever format it emerges, Nothing Matters will surely be its inarguable highlight, 1,200 people screaming along with Morris tonight as she bounces and spins around the stage for the set closer singing, "And you can hold me like he held her / And I will fuck you like nothing matters." For The Last Dinner Party, from here on in, the bacchanals are only going to get louder, wilder, more fantastical and ever more euphoric.