Mum’s, or to use its full title, Mum’s Great Comfort Food, is a restaurant in Edinburgh designed to soothe itinerant performance artists. For, in the fag days of August, as the Fringe dies — it will be reanimated next year by the blood of Citizen Puppet and Nicholas Parsons — assorted actors and comics and cabaret artists and mime artists and circus artists and ballet dancers and tap dancers and flute players and face painters and sketch performers and one-woman-show specialists (expiating rejection by standing in bins) and the guy who dresses up as Darth Vader are more ulcer than human being; and that is before we get to the clowns, who are in a special sub-section of desolation, even if Puddles Pity Party did get five stars. (‘Like Tom Jones, but taller — and dressed as a clown.’) Even people who make balloon animals are having an existential crisis; their hands move, twisting the balloons into, say, small neon-pink dogs, but their eyes are dead.

Mum’s is near the Gilded Balloon and the Pleasance Dome, ideally placed for performers addled by their drug of choice, which is hope. It is faintly American-diner and retro-misogynist in style. It has a gaudy sign with a wonky S (no Mum is perfect, you see) and a publicity board with a photograph of a bald Don Draper being presented with sausage and mash by a sexy Scottish housewife. Her sausages are faintly obscene.

Emma Peel is on the door of the girls’ loos, although no one who eats regularly at Mum’s should wear a leather catsuit, although they probably could anyway, such is its aura of acceptance; Michael Caine is on the boys’, although I doubt he knows it. (No one stays a movie star for 50 years by gorging on pies. This is the unspoken melancholy of Mum’s, which is, in its bones, a restaurant for failures.) The floors are black-and-white squares; the light is dim; the booths are tatty. It used to be called Mum’s Monster Mash Café but rebranded in 2010, probably because the word ‘monster’ scared the comics.

It is less a restaurant than a psycho-therapist; the waiters know this. They are CBBC-presenter friendly and treat everyone as an under-five. They remember names through multiple visits and look upon every transgression — dropped cutlery, smeared napery — with the indulgent eyes of Angelina Jolie seeking another child to steal. It has a faintly political manifesto on its menu, which could have been written by Mr Greedy from the Mr Men, with help from Noam Chomsky: ‘At Mum’s we believe “gourmet” can and should be for everyone, it doesn’t have to be all “poncey” and value prices should never be an excuse to use inferior ingredients or to serve up microscopic portions, we know you know better and so do we. Trust Mum’s to make it all better.’ It is Mum’s and clientele against a cruel world with limited financial opportunities for face-painters and creators of balloon animals; it is, in culinary terms, a hug from a Scottish woman with huge knockers. Obviously, there are queues outside.

The menu is large and critic-repellent: the food requires no skill beyond love and greed. We eat shepherd’s pie with peas; beef stew with dumplings, and pork sausages with mash. (Mum’s serves 16 variants of mash, five variants of sausage and three individual types of gravy.) We are too full for pudding — crumble, banana split and mini-doughnuts — which is testimony to portion size. None of it is delicate. It soothes with mass and warmth; it allows one to endure for one more night in the spotlight of your comedy club, or toilet; it is an adequate substitute for that which every performer seeks: applause.