Katherine Parkinson is undeniably on a roll. After TV successes in The IT Crowd and Doc Martin she proved her serious acting chops with Dead Funny and is now headlining the National Theatre’s transfer of Home I’m Darling.

So she is not a surprising choice for the joint venture by Avalon and BBC Arts whereby seasoned creatives were sponsored to write for the stage. Although her script for Sitting was the only actually successful project, seen last year on the Edinburgh Fringe and now refreshed and revived at the Arcola.

Although Hoard by Bim Adewunmi – a freelancer for BuzzFeed News and occasional contributor to the Guardian’s ‘Briefly Noted’ column – was cancelled at Edinburgh, the Arcola are giving it a second chance immediately following Sitting. If it’s as funny as her defence of negative tweets by fans of the New York subway, it should be interesting.

Sitting is deliberately static. Three life models each take a chair facing, in different times, their unseen portrait artist. Their monologues are variously comic, self-absorbed, occasionally boring, but at least two are realistic.

Parkinson clearly knows and loves her male subject best: painter-decorator Luke is a kind, try-hard young father-to-be struggling with casual employment and a demanding, withdrawn wife. He is made noble equally by Parkinson’s writing and Mark Weinman’s magnetic, resourceful performance.

Hayley Jayne Standing’s older sitter is more predictably the artist’s former lover, but she’s warm and convincing. Least successful in Sarah Bedi’s etiolated production is the character played by Poppy Fardell, a self-absorbed would-be actress, equally uneasy in her bright orange cardigan and ill-knit fantasies.

Actually I think Parkinson missed a trick with ‘Cassandra’ – the actors each pick Jaffa Cakes from an on-stage plate, but Fardell takes only the smaller and paler ones – presumably gluten-free – making that part of the plot could have given an unsympathetic character an extra dimension.

It’s a short play, but the threads are not even touched together, let alone tied, for an hour and I was annoyed, but not surprised, that the woman in front of me took her phone out twice and sent texts during the show.

It still needs a little restructuring, but when revealed, the portraits – by Saatchi artist Roxana Halls – are admirable.

until May 11