What do you get if you strand two former child actors on Long Island with nothing for company but their dad’s vinyl collection and the Bay City Rollers’ old wardrobe? Apparently The Lemon Twigs, the glorious answer to a question that nobody had ever dared ask.

Brothers Brian and Michael D’Addario are just 19 and 17 respectively and, on the face of it, bear all the hallmarks of hipster conceit: prodigiously talented sons of a musician with an assured flamboyance beyond their years, they raid the musical culture of 1970s - post-Beatles Paul McCartney, Todd Rungdren, Big Star, Rod Stewart’s haircut - like kids in a sweet shop to make lo-fi yet fantastical, structurally complex glam-pop.

If that prospect sounds offputtingly try-hard - the way Brian hammily declares “My Twiglets!” before opener 'I Wanna Prove to You' is a reminder of his past on Broadway - then you need only to let the pair’s melodies lodge in your brain. Debut album Do Hollywood can be overwhelming in its gleeful experimentation, but at its heart is some delightful songwriting. Supplemented by keyboard and bass, live the melodic lushness is brought to the fore with irresistible exuberance.

As if to prove their flair, Brian sings the first half of the show while Michael drums, and vice versa for the second. Save Michael’s impressively supple high kicks (you could pull a hernia just watching), the overall effect is the same as the pair take a magical mystery detour through their influences. At times songs are a patchwork of ideas: the Syd-Barrett-like 'Haroomata' breaks down into a frantic fairground swirl; set closer 'A Great Snake' is a mini-epic of changing tempos with a dreamy psychedelic outro. At other times, The Lemon Twigs are pure pop: the harmonious piano ballad 'How Lucky Am I?', sang beautifully by the brothers and keyboardist Danny Ayala, is genuinely McCartney-esque, while the chorus of 'As Long as We’re Together' is an arms aloft, festival moment-in-waiting.