“Be ready at 6am,” barks production assistant Aisling (aka Owen Sharpe) nervously pushing a lock of hair behind her ear.

In a flash, she crouches down, legs spread apart, rounded back, metamorphosing into gruff culchie, Mikey, complete with a thick Irish brogue.

Then, he straightens up, dusts himself off and becomes Jake Quinn, seamlessly slipping into his third character in barely two minutes – so seamlessly the mind frankly boggles.

His co-star (Kevin Trainor) too goes through a similar bout of (schizophrenic and frenetic) character flip-flopping – first a condescending producer, then a Hollywood prima dona – effortlessly settling back into his ‘main role’, salt-of-the-earth chap and fellow extra, Charlie Conlon.

Over the course of Stones in his Pockets, the unstoppable duo tot up 15 characters between them (including our two heros Jake and Charlie) bringing a truly motley crew to life with a simple flick of the shoulder, infinitesimal posture change and countless accent switches; rural Irish, posh Irish, Scottish, affected American… And it is a riot to behold.

Jake, Charlie and co are movie extras, herded and ordered around County Kerry’s wind-lashed countryside, and paid €40 a day for the privilege, by a Hollywood film crew, shooting a historical blockbuster about dispossessed peasants and a budding romance between a rich girl and a local farmer. The growing tension between the “natives” as they are so kindly referred to by producers and the Hollywood lot come to a head when tragedy strikes in the village.

Simply, yet cunningly observed, Stone in his Pockets hilariously captures the culture clash between the locals and the film crew and, more generally, the fraught extras/stars dynamic. The little people must take casual put-downs on the chin, bite their tongues and stay in their positions for hours on end, waiting for the real stars to deign to emerge from their trailers. And that's when they’re not roped in to boost the talent’s fragile egos! In one memorable scene, Jake is frogmarched to the winnebago of the period drama’s starlette, Caroline (Kevin Trainor at his sultry best), by a burly Scottish bodyguard (also Trainor) to help her improve her subpar Irish twang.

Through it all, Trainor and Owen never once miss the mark or fumble through their split-second transitions. Both laugh-out-loud funny and hugely affecting, Stones in his Pockets will have you in thrall – and stitches!

Stones in his Pockets runs at the Theatre Royal Bath until March 16 - Marion Sauvebois.