Suits you nicely, sir It's scary how long Robbie Coltrane has been away from the stage in this country. Now, after 15 years, he's making his return, in The Brother's Suit. Prepare to see a legend in your own lunchtime.

It is the end of the day for rehearsals of The Brother's Suit, Peter McDougall's new work for A Play, A Pie And A Pint, the ambitious series of lunchtime drama at Oran Mor, Glasgow, that has reinvigorated Scotland's theatrical old guard. The play will mark Coltrane's first appearance on a stage in this country for 15 years.

The BBC Club, meanwhile, hasn't seen Coltrane grace its doors for even longer. "I haven't been in here since we did A Kick Up The Eighties, " Coltrane muses as he tucks himself into the corner of the room like a naughty, if somewhat oversize, schoolboy. The "alternative" sketch show is just a memory now, though the club was "a good place for meeting people. Not that it's changed much, " he chortles, forensically eyeing up the detail of the room's crumbling, slightly musty decor.

"Look at that, " he says, scrutinising how the mantelpiece has been screwed on to the wall. "Someone's cut round the wallpaper with a scalpel to make sure it fits." He eyes up the garish, vertically striped pattern, and visibly twinkles. "That was the seventies for you."

The seventies was when Coltrane's generation, McDougall especially, was stirring things up in the drama department down at Queen Margaret Drive and when Coltrane himself was making a name for himself after appearing in the Traverse Theatre's first production of John Byrne's The Slab Boys.

A Kick Up The Eighties and The Comic Strip Presents made many presume he'd stepped out of the stand-up circuit, but Coltrane was headed for unlikely leading-man status. Rock'n'roll comedy drama Tutti Frutti did it for him in the late eighties, then a fascinating study of sozzled police psychologist genius Cracker in the early nineties.

Coltrane has also been a James Bond baddie, not once, but twice, and two years ago executive produced his own TV vehicle, The Plan Man. These days he's best known for his regular turn as Hagrid in the Harry Potter films. So why, just two weeks after his 55th birthday, go back onstage after so long away?

"It's good to scare yourself now and again, " he states flatly. "Having to learn the lines is hard, but in many ways we did the same on Cracker, because the directors liked to film all the interview scenes in one mastershot.

"So you'd be stuck in a hotel at 8am going over and over it, then you'd walk on and have to set the tone of things to make it work. I quite like that pressure, because it raises the level of your game."

The Brother's Suit is a tale of two siblings, one of whom may or may not have done the right thing, and is a follow-up to McDougall's last contribution to the Oran Mor programme, The Father's Suit. Given McDougall's background in gritty television drama, The Father's Suit stood out because of it's theatrically stylistic, non-televisual style.

The Brother's Suit promises more of the same.

Coltrane has been a pal for almost 30 years. "I think he probably started with a two-hour play, and just boiled it and boiled it until it was half an hour long. So it's so dense, if you miss a semi-colon you've killed a wee bit of meaning, " says Coltrane.

Despite that longstanding friendship, The Brother's Suit will be the first time the pair have worked together. "These things are all so much about synchronicity, " Coltrane shrugs. "Either I've never been suited to the part, or else I've always been busy on something else."

As he talks, he scribbles distractedly on his script. Such diversions are commonplace with Coltrane.

His last stage work was Mistero Buffo, Dario Fo's solo interpretation of the Mystery plays. Talking about it, he veers off on a historical discourse concerning the origins of the Mysteries.

A 1990 tour of the play left Coltrane alone onstage for a gruelling three hours. It was, he says now, "a beast of a thing to do". A few years earlier Coltrane had been equally exposed when he performed standup in Edinburgh as part of the 1986 Commonwealth Arts Festival in a show at the Ross Bandstand on Princes Street Gardens.

He is not happy to dredge up the experience. "That was awful. That's when I foolishly believed I could do stand-up, which I really can't. I never found a public persona for doing it.

The big illusion about comedians is that they're being themselves, but they're not. They're being something very like themselves, but I never got that, and thought I could just go on like I was in the pub. God, that was a big fright."

However, the recent screening of the entire series of Tutti Frutti as part of the Glasgow Comedy Festival speaks volumes of Coltrane's comedic talents. Coltrane is quietly proud of Tutti Frutti, and seriously considered going to the GFT for the sell-out screening, before deciding it probably wouldn't have been for the right reasons. He's delighted, however, by its continuing appeal.

"It's funny now, looking at programmes such as Clocking Off, Tutti Frutti was way ahead of all that. It was the first thing on television that was funny but also terribly moving.

In those days you either had light entertainment, or it was, " and he says it with a flourish, "drama. Tutti Frutti was like real life. Sometimes it was funny, sometimes it was sad, and sometimes it was both at the same time."

Saddest of all is that, for what Coltrane describes through gritted teeth as an ongoing "legal stushie", Tutti Frutti is unlikely to be rescreened on TV in the foreseeable future. Coltrane isn't specific about the dispute, though the ever-changing face of the BBC - its Glasgow club aside - may be in the thick of things.

IN THE GROUND-FLOOR BAR, THE main wall is covered with framed pictures of BBC stalwarts past and present. A group shot of the Balamory team nestles up to a portrait of Robert Carlyle, who appeared alongside Coltrane in one of Cracker's best stories, but here looks grim as Hamish Macbeth.

Coltrane stalks the room, scanning each picture with equally grim curiosity.

"I can't help but notice, " he deadpans at last, "there seems to be someone missing."His face widens with mock bemusement at how easy it is to rewrite the past. "I'll have to have a word."

The Brother's Suit, A Play, A Pie and A Pint, Oran Mor, Glasgow, Monday-Saturday, April 16, 1pm.