Live: Le Grand Début. Melody's Echo Chamber, Cargo.

As début LPs go, the eponymous intro to Melody's Echo Chamberreleased this week, coincidentally – was as strong as many, if not any. An oneiric whirl around chanson française swigged down with copious amounts of psych (a genre infusion to have come courtesy of Tame Impala's tonight, inevitably absent Kevin Parker) c'était un doux tour de force. And indeed as concerts débuts go, this one's commensurately special, if subduedly so.

Granted, it's somewhat outré a move for Melody Prochet to emerge from the 'Chamber for her very first headline showing this side of la Manche, but then she may not have that tropical allure of the other to her fellow Français. Certainly, a certain Gainsbourg has always found a warmer spot in the hearts of many in which she may nestle around these ends of things. And, flirtations with the French lingo momentarily binned, Prochet's bilingualism too is of utmost beguilement.

For Prochet is – or perhaps has been concertedly made out to be – a démodé romanticist. Flagrant gestures of affection are about as welcome round east London as Le Coq Sportif tracksuits, and yet Prochet somehow embodies a rakish enticement as intangible as the '60s. She epitomises the crème de la crème; the unfeasibly well endowed focal point of all playground envy as she coos dulcet nothings into a mic stand blooming variegated bouquets snatched from Girls' grave. Heck – she could've pinched 'em from Père Lachaise and it wouldn't make the whole aesthetic any less sweet.

She sweeps in on Endless Shore. Adorably reticent, her thanks are effusive and prove strangely heartwarming. She most probably means it. She most probably means every insouciant sigh she exudes, but even live they're veiled in an unintelligible mystique. This is the uncharted point at which twee meets freak-psych on the borders of folk, and it pongs of a certain je ne sais quoi. As may a Camembert. Fetid, therefore? Mais non! It is a delectable sonic sundae to be duly scoffed. There's always Mount Hopeless into which we may swiftly retire – a velveteen smooth as plush as any duvet. It's a thick blanket of warm and fuzzy thing; as enchanting as she herself.

What with this headlining malarkey being a step out into the great, wide inconnu the levels aren't quite where they ought to be from the back of the cavern but, as she flicks her dip-dyed mop with aplomb and we gyrate wildly for a Tuesday, that's quite alright as far as all are concerned, merci beaucoup. There's then the altogether divine I Follow You – a giddy waft filled with Jean-Michel Bernard idiosyncrasy and kitsch gesticulations. Where there may one day be strobes and spotlights set to a violent flicker, for the moment Prochet has but the interpretive flashing of gleaming white palms. This may make her out to resemble a del Toro ghoul, but she's in fact rather more Michel Gondry – an adorably awkward caricature snatched from The Science of Sleep.

Its guitars detached and ratcheted down a peg or two in Parker's absenteeism, her vocals are left all the more nude. And whilst it's not to say that they're in many ways nervy, they're not quite there yet. A tonight almost arabesque You Won't Be Missing That Part Of Me attests to that, as it does to Prochet's at times all too ingratiating lyrical content. She even does that deplorably clichéd thing of rhyming me with free. But, as she bubbles post-song and posthaste: "This is so much fun!" her evident amusement proves all too infectious for such reservations to linger any longer than that split-second in which they're first formed.

Although a residual scepticism remains. For in deriving such glee from her own pieces, it almost feels as though they're not truly hers; as though there's a truant ghostwriter meddling in the shadows. Plainly there's little alteration in approach to, say, Bisuou Maguique and an unremarkable rework of Serge's ode to Mademoiselle Birkin, Jane B. "Merci Serge; merci Chopin" she chirrups, exchanging thanks for apologies. Two consecutive songs in her mother tongue? Jamais!

Rather more insufferable, however, is the warmth within this arch of railway, where a Provençal heat has been allowed to stifle. It is, how you say? Il fait chaud. The atmosphere oppressive, Prochet assumes the tone of a forgotten Air vocalist on a faintly rambunctious Some Time Alone, Alone that's toughened up a touch. Generally speaking, the live show is a little less bedroom and a load more bombast, with this particular instance evocative of Deerhunter's hugely hi-fi Halcyon Digest endeavours.

Aptly, Quand Vas Tu Rentrer? comes lamentably close to an inevitable conclusion, as Prochet joshes: "If you buy our record, maybe next time we'll have a drummer!" Though if they're already ending these sorts of shows with the vertiginous high that Crystallized provides as its corrosive beats and acerbic licks fizzle out one final time, well, she's best going alone for the foreseeable. Peut-être...

For if otherwise it's all a little innocuous, Prochet's saccharine tones form the silver lining, or the delicate icing to a usually nicey-nicey that is here diced with something all the more malevolent. The band then erect your average barrage of whitish noise, before bringing it down quite majestically and as though Gondry Crate Paper swept along a Parisian boulevard on an outstandingly blustery matin, Prochet evaporates. Will she soon materialise once again? Moi, j'espère.