Want a single entendre? ‘Mrs Brown’ will give you one

For Agnes Brown, the Irish mammy with a filthy mind, a dirty laugh and a heart of purest treacle, there are no more worlds to conquer.

Brendan O’Carroll’s barrelling, cardiganed creation has been a radio star, a publishing phenomenon and a film character, anchoring a DVD series, a stage show and a TV comedy that was recently voted the best sitcom of the 21st century. And still, disbelievers despair, who watches this shit?

The answer here, according to astronomical audience share, can be as much as one in two people. Now that Mrs Brown has been granted her own chat show, in the BBC and RTÉ co-production All Round to Mrs Browns (RTÉ One/BBC One, Saturday, 9.15pm), you get to meet them.

“The best thing about the new show is that it’s going to include you, the audience,” explains the unsinkable Mrs Brown, as she guides us through the complexities of the new format – a variety show, with guests. In truth, the audience could hardly be ignored; about half of the hour-long running time is taken up with whoops, howls and applause.

It's easy to scorn broad comedy and very basic shenanigans, like the umpteenth time Mrs Brown gyrates to Shaggy's Boombastic with doe-eyed visiting Chef Ali, or readjusts her knickers on the delivery of another single entendre. But O'Carroll knows his audience. When Sandra, the winner of Mammy of the Week, is brought onstage, nominated by her daughter for her "potty mouth", it's like the introduction of a surreal mirror.

Lightly humiliated with the story of how she once mixed up her haemorrhoid cream with Deep Heat, it’s as though Sandra is one of O’Carroll’s own jokes magically sprung to life. The phenomenon begins to make sense.

The show is understandably more interested in its watchers than its guests – sitting at Mrs Brown's kitchen table, Pamela Anderson literally doesn't know where to look – and Sandra, the Mother of the Week, is later rewarded with a bounty of kitchen-themed prizes.

If Mrs Brown is your idea of fun, the show assumes, then a dishwasher and a year’s supply of tea must be your idea of heaven. (She also wins cash, in a flitter of five-euro notes, which – for a show set in Dublin, filmed in Scotland and featuring a mainly English audience – seems almost like a political statement.)

When guests Judy Murray and Anderson are largely quizzed about their children, though (Judy, a tennis coach, has created two tennis champions), and Judy's mother Shirley then arrives to be quizzed about Judy, the show's whole idea of motherhood – perhaps even humanity – feels like the ribbing sentiment of a greeting card bought last minute at a petrol station.

Mothers, the show assumes, are a homogenous tribe who enjoy cookery segments, the constant reminder that men are eejits, lashes of sniggering sexual innuendo and, of course, James Blunt.

And Blunt, whose syrupy ballads hide a wild streak of humour, makes for an appropriate guest. “I don’t understand why everyone thinks you’re a wanker,” offers Mrs Brown. “It is true,” replies Blunt, “I do like wanking.” Careful James, or they’ll make you come again.