What with the weather, the Tube and life in general, it seemed that nothing was going to winkle a smile out of me last night. How wrong I was. On entering the auditorium for this lovably ramshackle new musical from Iceland’s Vesturport company, we are greeted by a chorus of senior citizens having a right old singsong. Such enthusiasm from them means much grinning from us.

Love could do with lots more from these lovable OAPs — nonprofessionals all, plucked from the local area and seemingly inspired by America’s Young at Heart chorus, who have previously enjoyed great success at this venue — and their winning way with My Old Man Said Follow the Van. For much as the piece bubbles with community-spirited heart, there is an ill-planned muddle where the storyline ought to be and where the professional actors actually are. Gísli Örn Gardarsson and Víkingur Kristjánsson’s theme is love in the third age, represented here by an old people’s home but this potential dramatic goldmine of a subject is barely explored.

A lot could have been said about passion on a bus pass, of the snobbish preconceptions of the young that romance is their terrain and the unsettling effect on grown-up children when elderly Mum or Dad suddenly come over like skittish teenagers. Sadly Gardarsson and Kristjánsson say virtually none of it. They offer instead the unconvincing liaison between Margaret (Anna Calder-Marshall), whose son has consigned her to the home while she recovers from a broken arm, and dementia-sufferer Neville (Julian Curry), watched over by a nurse who is equal improbable parts Ratched and Carry On film.

Far too infrequently, that delightful chorus pipes up with snatches — never more than a few lines; perhaps there are copyright issues? — of popular songs. “You’re going to reap just what you sow”, that haunting thought from Lou Reed’s Perfect Day, has extraordinary resonance when delivered with this combined weight of years. Coming from a standpoint that’s far nearer the grave than the cradle, The Who’s My Generation becomes a counter-intuitive delight.

All they need now is a proper plot.

Until 21 June (0871 2211 722, www.lyric.co.uk).