DAVID Greig – the playwright who has, since 2016, been artistic director of the Royal Lyceum Theatre, Edinburgh, and the author of such excellent and eclectic dramas as The Architect, Dr Korczak’s Example and Casanova – is widely considered (including by me) to be one of Scotland’s finest stage writers. Which leaves me – and, I suspect, a significant proportion of the Lyceum audience – at a loss to explain Two Sisters.

The play is the first original drama – as ­opposed to adaptation – of his own that Greig has programmed at the Lyceum. To say it is a disappointment would be like saying that Jacob Rees-Mogg is annoying – that is, accurate but ­entirely insufficient.

Set in the dog-eared, cliff-top caravan park Holiday Heaven in Fife, the play – a ­co-production between the Lyceum and the Malmö Stadtsteater – is teeth-grindingly clichéd and predictable.

The National: Two Sisters review: A caravan   of clichés

The ever-excellent Jess Hardwick plays thirtysomething Emma, a pregnant corporate lawyer and wannabe fiction author who is ­unfulfilled by her boring marriage to a Christian ­businessman, has decided to use a caravan at the park (the ­location of family holidays during her childhood) as a writer’s retreat.

The never-less-than-superb Shauna Macdonald joins the cast as Amy, Emma’s slightly older TV staffer sister, is cursed – or blessed, according to taste – with a super-active libido. She arrives in search of shelter following her long-suffering husband’s discovery of her latest multiple affairs.

These caricatures are confirmed, with Emma wearing a long, relaxed white dress and ­sandals and looking like a wholesome extra from The ­Waltons, while Amy appears like Tina Turner circa 1985 (all black, leather miniskirt and ­studded stiletto heels).

The catalyst in the women’s ensuing midlife crises scenarios is Lance, the holiday camp’s longstanding caretaker and DJ – a self-described Fifer with an incongruously Swedish accent. Played by Erik Olsson, he is a two-dimensional, dope-smoking, yoga-practising hippy, and a hit with the gaggle of teenagers who, inexplicably, hang around Holiday Heaven.

The National: Two Sisters review: A caravan   of clichés

Anyone who saw the unforgettably brilliant üBUNG, by Flemish company Victoria, when it came to Glasgow way back in 2001 (or, in more recent times, the work of the astonishing, but sadly now defunct, Glasgow youth company Junction 25) knows that deeply profound work with teenagers is possible if the young people are properly invested in it.

By contrast, in moments that are ­excruciatingly anti-theatrical, Greig asks the young chorus to read out audience members’ memories of their teenage years between scenes, before ­putting them at the service of some ­ludicrously ­histrionic moments of melodrama towards the end.

The National: Two Sisters review: A caravan   of clichés

Given the disastrous shortcomings of the script, it’s hard to see what the talented ­director Wils Wilson could have done to improve ­matters (apart from, perhaps, advising Greig that sensible Emma would be extremely unlikely to drink herself into a memory-erasing stupor while pregnant). Asking award-winning actors such as Hardwick and Macdonald to perform this ­nonsense is akin to giving Olympic ­swimmers a paddling pool to play in.

Two Sisters is, surely, the worst Greig ­drama to ever land on a stage. It’s certainly an ­embarrassment to the illustrious Lyceum.

Until March 2: lyceum.org.uk