FROM tonight, viewers of terrestrial telly are going to see the Motherwell mumper, Tam Cowan, doing what he's become very skilled at doing: subjecting football folk to a friendly mugging. Three years after its humble beginnings on digital television, Cowan's irreverent football fanzine Offside switches to mainstream BBC1.

Offside's initial run of 10 shows will largely adhere to the show's established format. Essentially, this consists of Tam being genially rude about/brutally honest to a pair of football-related guests each week. Offside co-producer Tony Followell has been with the show from its inception, and is well placed to analyse Cowan's no-nonsense interviewing style.

''Most football interviewers want to be loved by their subject and become their pal, whereas Tam's always had this appetite for destruction - if a guest on the show doesn't like him, it's their problem,'' says Followell.

''No guest has ever fallen out with him, though. If they're ex-players, they seem to enjoy the chance to laugh a little at their past. It's a grilling, but a likeable one - and it's conducted at a matey level of abuse that they're comfortable with.

''I'll never forget the time we had TV presenter John Leslie on in his capacity as a celebrity Hibs fan. You could see he was really wary throughout the whole half-hour. He just knew that at some point Tam was going to make some scathing reference to his former fiancee, Catherine Zeta Jones.

''Naturally, Tam being Tam, a cunning kind of monkey, he left it right till the end of the show, during the final quiz section. Very casually, Tam asked John: 'What would you call a man named Michael who's lost his dog?' John knew he was being sent up somehow, and umm'd and ah'd, but couldn't head it off. 'Michael dug-less!' Tam beamed with a triumphant chortle.''

Tam's appetite for pithy schoolboy puns is likely to be undiminished, but there are a number of other notable changes to Offside. Principally, it's no longer an in-house BBC Scotland production, but a joint effort with Glasgow indies The Comedy Unit.

Comedy Unit main man Phil Differ is thus Offside's new co-producer, and he'll be bringing with him one of his most successful TV creations. ''Every week, we're going to have Jonathan Watson in a topical three-minute mini-version of Only an Excuse - Only a Wee Excuse,'' reveals Differ.

''Johnny will probably be doing three characters a week. So you'll have Tam's opening monologue followed by Dick Advocaat talking about the vital issue of that week to Alex Ferguson and Martin O'Neill, say.''

Other changes involve Offside being filmed before a live audience on a set that Differ describes as ''Las Vegas meets Tam and goes to Fir Park for half-time pies and Bovril - Viva Lost Waistline!''

Followell is meanwhile keen to stress that the show's inter-active element will be upped. ''Throughout his time on Radio Scotland in Off The Ball as well as with Offside, Tam has always had football fans sending him in all sorts of bizarre football memorabilia. Ultra-realsitic homemade plasticine models of pies. Football programmes with amusing misprints.

We've also been sent all sort of daft lookalike photographs, plus loads of snaps of Stuart Cosgrove in peculiar pre-match circumstances during his many trips abroad to support Scotland over the past 30 years - usually of Stuart looking dodgy in gents' lavatories in soccer stadia from Wembley to Monaco to Belgium.

''We also once got sent some very revealing photographs of a group of Kilmarnock players on a club night out. They revealed an intriguing dimension to what might be termed one Killie player's tackle. We very much want our studio audiences to turn up with all sorts of stuff like that.''

Offside's initial run of 10 programes will end somewhere around Christmas. A second 10-show season will thereafter ape the SPL's mid-winter break in reopening on January 28. On top of that, Offside's team hope they'll be able to get a result at the end of the day and be allowed to enter extra-time with a Scottish Cup final special edition. Obviously, the Offside boys will have gived 110%.

Says Differ: ''It's what Tam is best at. He's truly on home ground whenever he's asked to be humorous about football. In fact, I'm sure everyone who loves football will come to look upon Offside in the same way that music-lovers view Spinal Tap. I'm a massive music fan and when I first saw that film, I remember coming out of the cinema thinking to myself: 'At last! A movie that's been made especially for me'.''

In at least one respect, Tam Cowan will undoubtedly follow the true Spinal Tap tradition: he'll have the volume-control on his wit turned all the way up to 11.

Offside begins tonight on BBC1 at 10.35pm. Erstwhile TV pundit and former Motherwell, Liverpool, and Scotland star Ian St John will be one of the show's first two guests. Non-footballing folk of a nervous or sensitive disposition are advised to seek medical opinion before tuning in.

OFFSIDE

THE SIX-MAN TEAM AT THE HEART OF THE PROGRAMME SPORT A WIDE RANGE OF ALLEGIANCES

Back catalogue

IN its original digital incarnation over three seasons on BBC Choice Scotland, Offside racked up 108 editions between September 1998 and March 2001. Host Tam Cowan has thus jousted with over 250 football-related guests, from departing Scotland manager Craig Brown to former children's TV favourite (and Ayr United fan) Glen Michael.

Award-winning

In 1999, Offside won a Royal Television Society award: Regional Sports Entertainment Show of the Year. The award was handed over at a glittering ceremony in London by Ally McCoist. In view of recent events, McCoist's debut on Offside may be some way off yet.

Team players

The six-man team at the heart of Offside sport a wide range of football allegiances. Most famously, Tam Cowan supports Motherwell while Jonathan Watson supports Rangers. Co-producers Phil Differ and Tony Followell support Celtic and Kilmarnock respectively. Writer and script editor Rab Christie is a devotee of Partick Thistle. Fittingly, kilt-wearing director John Frame supports England's most Scottish club - Plymouth Argyle.

High jinks

Three memorably daft moments from Offside's history: 1) agent and commentator Gordon Smith responding to accusations of flagrant wig-wearing by flaunting a Jackie Bird-inspired scarlet toupee; 2) Tam Cowan being subjected to a violent water-pistol attack by pundits Murdo MacLeod and Stuart Cosgrove; 3) Herald sports writer Graeme Spiers publicly outing himself over his loving relationship with Elton John - by sitting at a piano and playing Elt's Your Song in a duet with Tam.

Complaints

Offside's final season on digital TV was broadcast nationally on BBC Choice, and not merely in Scotland. This move to UK-wide transmission prompted an increase in viewer complaints to the BBC. In particular, there were repeated phone calls angrily asking for Tam Cowan ''to learn to speak in recognisable English''. Most of these calls came from his mum.

E**********!

Never a man to call a flipping shovel a blinking spade when he can call it a chuffing digging implement, straight-talking Partick Thistle manager John Lambie holds Offside's record for deleted expletives - eight bleeps in a five-minute interview.

Free tickets

Over the past three years, there have been three on-location editions of Offside. These were filmed at Hampden Stadium, Curler's Bar in Glasgow, and The Hunting Lodge, Kilmarnock. Oddly, there has yet to be an Offside outside broadcast from Tam's native heath, Motherwell. This is thought to be linked to impoverished Lanarkshire locals' 100% inability to pay their BBC licence fee.

Offside will be recorded before a live audience every Monday night in BBC Scotland's Studio A at Queen Margaret Drive, Glasgow. Kick-off is at 7.30pm. Tickets are available free from 0141 305 6602.