Midsummer is billed as “a play with songs”.

Written by David Greig and Gordon McIntyre, it was a favourite at the Traverse in Edinburgh last summer, and its arrival in London is a welcome winter warmer.

Two thirtysomethings, Bob and Helena, meet in an Edinburgh bar.

They’re not an obvious match; Helena is an elegant lawyer, Bob a feckless small-time criminal.

Still, it’s a Friday, and midsummer madness ensues: they have unsatisfactory sex, then head off in separate directions, only to be reunited later in the course of a weekend that turns out to be a riot of hedonism and soul-searching.

The writing is sharp and observant. Those who know Edinburgh will feel an acute sense of recognition. And anyone who’s had a misguided yet joyous tryst will find much to savour.

The songs are folky and lo-fi — undeniably slight but appealing all the same — and they’re neatly performed by the actors, who strum acoustic guitars.

As Bob, Matthew Pidgeon exudes self-deprecating charm, while the beguiling Cora Bissett is altogether saucier, and David Greig directs with a storyteller’s sure touch.

Midsummer is not just enjoyable but original to boot.

There are not many modern romantic comedies for the theatre, and for the usually political Greig this is an experimental foray into the land of Richard Curtis and Nora Ephron, albeit with a great deal more sass.

The result is touching, knowing and humane, and comes complete with the familiar yet pleasing moral — spotted by Bob and Helena on a car park ticket machine — that “change is possible”.

Midsummer — until 6 February. Information: 020 7478 0100.