Al Murray is telling a Jewish joke. And Davina McCall and Brian Ferry are joining in. And, oh, look, there's actor Miranda Hart. And Boy George.

And writer Sanjeev Bhaskar (whose shrug goes right up past his ears). And that burlesque dancer, the fabulously named Immodesty Blaize. And comedians Shazia Mirza and Phil Cornwell. And tv presenter Jamie Theakston. And isn't that Graham Norton?

Quite what all these studiously non-Jewish celebs are doing is a mystery swiftly unravelled. They are, together with the cream of Jewish showbiz, gathered at the behest of actor and columnist Tracy-Ann Oberman, in this year's UK Jewish Film Festival trailer, "So, Mrs Cohen..."

Tracey-Ann has been named the festival's first ambassador, after having been a UKJFF patron for several years.

This year's festival has a comedy theme, and besides films, will include two programmes which will feature live comedy and discussion.

It has become a tradition to have a dedicated film trailer to precede all screenings: last year's, marking the UKJFF's 13th year, took inspiration from the Jack Rosenthal film, Barmitzvah Boy. Tracy-Ann, who has wanted to make a film about Jewish humour for some time, decided to make comedy the focus point of this year's trailer film.

She said: "My idea was to open up the subject of Jewish humour to contemporaries of mine in the industry I admire, both Jewish and non-Jewish. This married very well with the remit of the festival which this year wants to have a big comedy strand and also a broader appeal.

"I aimed to find the cheesiest Jewish joke imaginable and then get the interviewees to dissect it, whether they thought it was funny; if so why, and if not, why not, and to analyse whether Jewish humour was inclusive or exclusive to being Jewish."

And dissecting this truly terrible gag, shrugging and armwaving and holding up notices saying they reckon it is antisemitic (David Baddiel) and curling their lip and saying what a rotten joke it is (Jay Rayner), are dozens of actors, writers and presenters, many of whom will surprise audiences.

We should not forget the high-profile Jewish contributors, from Steve Furst (the man in the Orange phone commercials), Vanessa Feltz, Maureen Lipman, to American Jewish comediennes Ronna Glickman and Beverly Ginsburg - and even Rabbi Lionel Blue, who has been known to tell a dreadful Jewish joke or two in his time.

Tracy-Ann said: "Everyone interviewed was a friend either of myself or Harvey B Brown, the director. Basically, we took a camera and filmed everyone when they were free. For example, I knew that Sanjeev Bhaskar, an old, old friend, would always cite Woody Allen and Mel Brookes as great influences when he was writing for Goodness Gracious Me. He had a lot of insight into Jewish comedy.

"Boy George was wonderful because he has always had very close Jewish friends, but can still equate it all with his Irishness. Miranda Hart was utterly charming and felt that the joke could be about anyone, not necessarily a Jewish woman. Bryan Ferry was delightful, as was Davina.

"The editing and fine timing of getting the joke's rhythms right, was a massive job, done through the nights with top editors and sound mixers by blagging favours from people that both Harvey and I have worked with over the years. "

The trailer 'So, Mrs Cohen' will be shown before each screening. The UKJFF runs from Nov 4-21. Or look online at www.thejc.com

So, Mrs cohen, just how bad is it?

As for the Joke... it is indeed the cheesiest, and probably hoariest, that could be found, concerning as it does the JC's very own classified advertising department.

This is how it goes: Mrs Cohen calls the classified line as she wants to place an announcement. She says: "Morris Cohen's dead." That's it? asks the classified manager. "Yes," says Mrs Cohen, "that's it." But, urges the JC man, "you're entitled to six words. You get three more. And they're free." Mrs Cohen says she will think about it. Finally, she rings back. After due consideration, she has found her three missing words: "Morris Cohen's dead; Volvo for sale."

Watch the trailer here