Heard the one about the hilarious older woman?

The success of Tracey Ullman and Joanna Lumley in new sketch shows bucks the trend for women to disappear off screen after the age of 40

Walliams and Friends (BBC)

If you're a woman over 50 and want your own show on television, get a sense of humour. If that sounds flippant, it is not meant to. But it is striking that the last two new sketch shows to appear on mainstream television have starred Joanna Lumley, 69, and Tracey Ullman, 56.

The latter returned to British screens last week for the first time in 30 years. Ullman has spent those past three decades becoming very rich and famous in America thanks to The Tracey Ullman Show; she discovered The Simpsons, among other things, and was the top female comedian (worth £77m) in the Sunday Times Rich List last year.

Her return to the BBC is quite a coup, so it is odd that it has buried the show at 10.45pm on a Monday - even more so because, for a mainstream sketch show, it was much more hit than miss. Her impressions of a kleptomaniac Judi Dench and a sexy Angela Merkel were particularly strong. The final tap-dancing routine in a library - choreographed by Stephen Mear, no less - went on a bit but couldn't help but raise a smile. This was confident stuff, sparklingly delivered by Ullman with a cracking supporting cast and a writing team including Arthur Matthews (Toast of London) and Georgia Pritchett (Veep, Miranda). If all sketch comedies got that treatment, we might be able to stop wondering where the next Big Train is coming from. (Incidentally, I have an inkling on this: check out People Time, which got a very poorly scheduled pilot last year, on iPlayer if you want to see the young future of sketch comedy.)

Lumley appeared as David Walliams's sidekick in his new show, Walliams and Friend. It aired on Christmas Eve and was notable mainly for Lumley stealing every sketch she was in. Anyone who has relished her in Ab Fab will know that she is not afraid of making a fool of herself - I will never forget Patsy falling out of a cab and into a grave at Eddy's father's funeral - but this was something else. Lumley played a bitchy tanning salon owner, a vengeful wife, Mary Berry and more with spot-on timing. If they decide to make Lumley and Friend next, I'm in.

Joanna Lumley stole the show in the first episode of 'Walliams and Friend' (BBC)

There are other older female faces on television. The Dames - Judi and Maggie - do alright, and there will always be parts for marvellous actresses like Frances de la Tour, Anne Reid and Penelope Wilton. The tendency, though, is for older women to fade from view before they hit 40. Last week, I interviewed Sian Gibson, aka Kayleigh from Car Share. Now 39, she was offered plenty of work at the start of her career but once she hit her thirties, it dried up. By the time Peter Kay offered her the part in Car Share, she had given up on acting and was working in a call centre.

Now she is part of a generation who are hitting their comic stride in their forties. Ruth Jones, 49, is back in a fifth series of Stella, while queen of darkness Julia Davis, 49, has just finished a second series of Hunderby and returns later this year in Morning Has Broken. Catastrophe, co-written by Sharon Horgan, 45, is one of the best things on TV and Catherine Tate, 47, landed a plum spot in the festive schedules for her belligerent pensioner Nan.

Ullman says she was tempted back to the BBC by two women: the BBC1 controller, Charlotte Moore, and head of comedy, Myfanwy Moore. It was amazing, she said, “Just to be in a room at the BBC with two women talking comedy. When I started at the BBC it was five men in bow ties talking about the war.”

Some things change, but talent never gets old.