Can you believe that old people fall in love? That's basically the premise of this wrinkly rom-com starring Diane Keaton and Brendan Gleeson as Emily Walters, a widowed American who lives in a posh flat in London's Hampstead, and Donald Horner, an eccentric Irishman who lives nearby in a shack on Hampstead Heath.

Both characters are getting on a bit, which is fair enough given that Keaton is 71 and Gleeson 62, and lead vastly contrasting lives. She spends her days helping out in a charity shop and fussing over her son, while he scavenges and washes in a pond.

One day their paths converge when Emily sees Donald being attacked – and an unlikely alliance is gradually formed.

Apparently the script is very loosely based on the true story of Sligo man Harry ‘The Hermit’ Hallowes, but what you're getting here is basically a bog-standard romantic comedy that happens to be about older people.

Although it reeks of being a Notting Hill for the over-the-hill, Hampstead also owes a lot to The Lady in the Van, the film adaptation of Alan Bennett's play about a woman who plonked herself in a dilapidated van on his driveway for 15 years. England is full of such people.

Although relying too often on rom-com formula for laughs, Hampstead has its moments as Emily finds herself being drawn into Donald's world, and ends up supporting him as he takes on evil developers, who'd rather make money from a new luxury apartment complex than see some old crusty live contentedly in a corrugated box.

What it lacks in a script that's also painfully 'right-on' is compensated by a fine cast in a quirky and charming piece of cinematic souffle with Keaton and Gleeson in sparkling form. It's fun.