What the fuck to make of Russell Brand? At first he seemed easily dismissible as a lineal descendant of the Wacky Family Tree of TV Presenters. You could imagine some Deuteronomy style verse in the future recalling "Timmy Mallett who begat Chris Evans who begat Russell Brand and, lo, the world did weep...". Yet now he has transformed himself into a national institution (the type they put your Aunt Doris in when she started eating cat food). Something of a household name, he dresses like a Dickensian supervillain and talks and acts like he's rushing through the matinee performance of Jack and the Beanstalk at the Theatre Royal, Brighton.

"Brand ambles around the studio like Roald Dahl's Big Friendly Giant diving into the midst of the audience, becoming overly tactile, baffling them with bizarre questions and generally being an overbearing smart-arse."

All of which makes Big Brother's Big Mouth really quite gripping viewing. Having dispensed with the more formal Big Brother's E-Fourum format Big Mouth removes the Question Time desk, offers more audience participation and a lot more of Russell. Brand ambles around the studio like Roald Dahl's Big Friendly Giant diving into the midst of the audience, becoming overly tactile, baffling them with bizarre questions and generally being an overbearing smart-arse. And the audience love it. He is often very funny and seems to know where he is every second the camera is on him.

"Vanessa Feltz... never less than willing to rattle off her insane opinions and give full value in her role as batty old witch."

He doesn't miss a trick and will simply not allow any lull in the proceedings. The "celebrity" guests brought in to comment on events in the Big Brother house often have little to say for themselves bar parroting back what the audience have just said and he won't let them off the hook, pummelling them with questions until they earn every penny of their £30 appearance fee. Vanessa Feltz is a notable exception to this, never less than willing to rattle off her insane opinions and give full value in her role as batty old witch.

Like Davina McCall, he is a recovering heroin addict and being one of those hugely self-aware narcissistic types he refers to this plenty in his stand-up and Big Mouth monologues. He also moonlights as a tabloid shag monster having apparently done the nasty with living skeleton Kate Moss and Big Brother inmates Kate, Becki and Makosi. He often references the public perception of him, discussing the "womanising circuit" he belongs to comprising channel swimming nookie king David Walliams and EastEnders love skunks Michael Greco and Dean Gaffney telling increasingly lurid fictional tales of their conquests and rivalry.

"It being ostensibly a public forum we unfortunately have to deal with members of public."

It being ostensibly a public forum we unfortunately have to deal with members of public coming out with stuff like: "I like Glyn - fancying that woman with big knockers and dyeing his hair blond". Doesn't take much to keep you happy, obviously. Although the phone calls to contestants' friends and relatives can throw up the odd gem as in last night's episode when Jennie's mom addressed dismal panellist Gina Yashere "to the lady who said Jennie was up Aisleyne's arse - at least she's small enough to get up there". The practicalities of that manoeuvre notwithstanding, it was pretty damn funny at the time.

"Brand credits his audience with a lot of intelligence and you need to be alert to keep up with the scattergun allusions, asides and mimicry."

Brand credits his audience with a lot of intelligence and you need to be alert to keep up with the scattergun allusions, asides and mimicry he fires from all angles. He has a good ear for the vocal quirks of the BB contestants, notably with a memorable impersonation of Susie "I nearly went A over T and I nearly banged my self on the C, it reminded me of a time when I was with my husband actually, he wanted to put his D into my C and he said 'can I put it into your A?', I said 'you'll be lucky if I swallow your S!'". How she would blush.

When Davina McCall finally has the Big Brother microphone wrested from her cold dead hands I can think of few more interesting choices than Russell Brand as her replacement. Defying description and simple pigeon-holing, the only thing you can definitively say about him is that he's good television - something you haven't been able to say about Davina for some time.

The best thing about it: Call me oddball but I like Rosebud the horse

The worst thing about it: Idiot members of the public being idiots.

The verdict on Big Brother's Big Mouth: More entertaining than the parent show, at the moment.

Marks out of 10: 8