Let’s start with a nightmare. Wendy Wason, an Edinburgh comedienne, travelled to LA last year accompanied by her husband, who promptly succumbed to a fainting fit. Wason called an ambulance, unaware she was in a hospital car park, and was handed an £8,000 bill to cover the 15-yard trip. By the time her husband had been cured, the invoice had risen fivefold. As comedy Wason’s show (at the Gilded Balloon) is wry, downbeat and hilarious. It also has a Wider Purpose. She believes that US-style healthcare is about to engulf Britain and she wants us to help her save the NHS. Always a dilemma, I find, when stand-ups dabble in politics. Is the comic promoting the cause, or the cause the comic? As we left we were handed tin badges with the legend ‘Wendy Wason’ printed in far larger letters than the campaign slogan. Which was a relief. No dilemma there.

The Trial of Jane Fonda (Assembly Rooms) is based on a true story. In 1988, Fonda was about to shoot a movie in an American backwater but a group of Vietnam veterans vowed to run her out of town. She agreed to meet them. Their encounter is interesting, rather than gripping, and the play is short of suspense or high stakes. The characters seem to have been rustled up from the Cliché drawer. The soldiers are sweary, inarticulate lunkheads who wear baseball caps and combat fatigues. Fonda wafts about in a lovely combination of upmarket summer casuals. And she never once loses her poise, her articulacy or her apple-cheeked forbearance. The show’s highlight is a great performance from Anne Archer. She’s pushing 70, but not very hard. She could pass for 40.

Mark Farrelly’s one-man show about Patrick Hamilton (Laughing Horse) offers a horrifyingly funny snapshot of the wit, novelist and playwright. He was at his best when satirising his father. ‘I served on the Somme. Well, someone had to do the catering.’ Later he imagines his father, as a hostage of old age and incontinence, complaining, ‘A nurse has to hold my manhood with cake-tongs.’ Hamilton was among the greats of the 20th century but success couldn’t protect him from the lure of the bottle. This brilliant hour-long show, hidden away on the free fringe, deserves amplification and a wider arena. Probably television.

It’s amazing how many performers treat Edinburgh as a suburb of London. Rosie Wilby: Nineties Woman (Voodoo Rooms) is a scrapbook of student memories that would go down well at a lesbian refuge in Peckham. Similar problems afflict Emma Packer’s monologue CTRL+ALT+DELETE (Zoo Southside), which assumes that Edinburgh is fascinated by the chippy angst of Brixton rude gals. Packer creates a character called Amy, whose rhetoric and performance embrace every platitude in the rapper’s handbook. ‘D’govmint ignores u, d’media laughs at u, d’pleess fight u an dey win,’ she wheedles. And yet Amy is a white blonde whose bad-girl persona is a pose that makes her feel comfortable around her black mates. She’s also a law graduate, studying for the bar. ‘D’pleess fight you an dey win’? Not really, Amy. ‘D’pleess pay u tunsa dough 2 repreezent dem in homicide cases wich u win 4 dem.’

If only they’d watched Jim Davidson, a master of his art (Assembly Hall). Davidson has the good sense, and the courtesy, to adjust his act to local predilections. He starts by mocking the shabby unswept stage where he stands in front of a drape held up with staples. ‘The festival phoned me. “Jim,” they said, “there’s nothing we won’t do for you.” And look. They kept their promise.’ He delivers an hour of dazzlingly funny gags, which he organises around the central figure of his father, a Glaswegian crock, who emigrated to London in search of work. The gabbling Clydeside soak is an archetype that works nowhere better than in Edinburgh. But the routines are a mere ornament to the legal centrepiece of the show. Davidson is an innocent graduate of Operation Yewtree, which haunted his life for 12 months and deprived him of half a million pounds in lost earnings. Every complaint of molestation has been withdrawn. Among his accusers was a chorus girl, whose stocking suspender he had twanged during a gig in 1978. ‘Sexual assault?’ he says, incredulously. Over a tea break in the midst of his interrogation he asked the detectives to explain to him, off the record, what lay behind the witch hunt. The cops said they’d been ordered to treat all allegations as true ‘unless proved otherwise’. As Davidson uttered these words, a shiver of outrage ran through the venue. Yewtree was mandated to find abusers and to pursue justice while upholding the presumption of innocence. Davidson’s experience suggests that Yewtree has subverted liberty and turned the police into the poisoners, and not the custodians, of freedom.