LAST one in’s a rotten egg! Sisters Bif (Celia Imrie) and Sandra (Imelda Staunton), noseplugs and all, brave a swim in winter. Photograph courtesy The Culture Concept Circle.

WHAT DO YOU do after 40 years of marriage to a man with a social standing, when you find he’s been canoodling with someone else for long enough to make it serious? If you’re Lady Sandra Abbott (Imelda Staunton), you furiously and tearfully tootle off to your big sister, Bif (Celia Imrie), with matching luggage in hand, even if you haven’t seen her for ten years and at best your relationship with her is rickety and judging. This is the starting point for Finding Your Feet, a British romantic comedy about love, loss, sisters and forever.

The grand narrative of the tale, which uses social dancing as its nub, is as clichéd and syrupy as you can possibly imagine, but it’s the manner in which the work is populated, written and performed that will make you forgive every well trodden piece of predictability as you mop your snot and tears with abandon, holding back on the huge sobs for fear of embarrassing yourself amongst strangers.

Staunton and Imrie absolutely sparkle in their embrace of these two sisters, in terms of the social values and wild idiosyncrasies each represents and their sibling intersections: it’s not an immediately lovey-dovey forgiving relationship. Rather, it’s quite a tough one, which touches on messy interiors and deep secrets, rendering women probably in their 70s still subject to the little sweet and sometimes spiteful things they did as small girls. And, as is the wont of British comedy at its very best, the texture of the work is developed with such a fine sense of dark humour, you will laugh until the tears flow copiously.

You’ll also cry with the same sense of abandon. And just when you think you can’t cry any more, the film turns a corner and you begin to weep with joy. The plausibility offered by this splinteringly fine cast which also includes Joanna Lumley as Jackie, Timothy Spall as Charlie and David Hayman as Ted, the dance mates. It’s about growing older with unapologetic flamboyance and living for the moment as it comes.

It’s a tonic of a film, in the same kind of genre as Film Stars don’t die in Liverpool and to an extent, The Leisure Seeker, which will haunt you if you’ve ever had a sibling, or let a dream go, or felt trapped in a context which in your deepest heart you know isn’t yours. Or even if you will never see 50 again. But more than that, it’s also an extremely moving foray into the reality of dementia and how it impacts on one’s loved ones in ways that are seldom discussed on the silver screen.

Don’t see this film without lots of tissues on hand, and hold off on that mascara. This is a real weepy, but one that’s as good as it gets.

• Finding Your Feet is directed by Richard Loncraine and features a cast headed by Anna Afferri, Alister Albert, Christina Avery, Alex Blake, Kaye Brown, Clare Cashion, Peter Challis,  Paul Chan, Rochelle De-Terville, Sonny Fowler, Samuel Gaspard, Fred Folkes, Avril Gaynor, David Hayman, Dollie Henry, Richard Hope, Celia Imrie, Josie Lawrence, Heather A Lewis, Teresa Lucas, Joanna Lumley, Christopher Molloy, Jill Nalder, Phoebe Nicholls, Niall O’Loughlin, Frankie Oatway, Kenn Oldfield, Marianne Oldham, Indra Ové, Basil Patton, Jacqueline Ramnarine, Steve Saunders, John Sessions, Raven Shanelle, Timothy Spall, Imelda Staunton, Karol Steele, Fran Targ, Sian Thomas, Sarah-Jane Tindle, Philip Tsaras, Victoria Wicks and Patricia Winker. It is written by Meg Leonard and Nick Moorcroft. Produced by Andrew Berg, Meg Leonard, Nick Moorcroft, John Sachs, James Spring and Charlotte Walls, it features creative input by Michael J McEvoy (music), John Pardue (cinematography), Johnny Daukes (editing), Irene Lamb (casting), Jon Bunker (production design) and Jill Taylor (costumes). Release date: May 24 2018.