"Benson and Hedges won't fit!"

"OK, folks, candles at the ready . . . "

"Did we get the steps, anyway?"

"Hmm. I'm not sure about this."

On a surly January afternoon, Lecture Room Number Two at the Irish Writers' Museum in Parnell Square is playing host to a very special rehearsal. Frazzlement, amusement, satisfaction and frustration are present in roughly equal quantities: though there's nothing very special about those, the raw material of all rehearsals everywhere. But when Des Keogh and Rosaleen Linehan bound on to the makeshift stage and launch into a speed-of-light patter on the topic of hit movies which rhymes "blind and gay" with "IRA" and "Chinese beggar" with "Schwarzenegger", something magical happens. For this is the revue revisited. The pair haven't done a comedy two-hander for 15 years - not since Two-Faced, in February 1985 - but the minute they open their mouths to sing, it's as if they've never been away.

Once upon a time (actually, from the mid-1970s to the mid-1980s) the names Keogh and Linehan were synonymous with anarchic musical comedy of the satirical kind. More recently, of course, the pair have gone "serious", Keogh with his radio show Music for Middlebrows, Linehan in a series of acclaimed stage and screen roles which culminated in the award-laden Dancing at Lughnasa. So what made them rewind towards the revue format?

"Well, we did some charity concerts in the Gaiety," explains Keogh. "The first was a tribute to a former stage director of ours; the second a tribute to Maureen Potter. And they went down really well, so we kept saying, `hey, we must get back together and do a full show'. Every time we met we said it, but we never did it. But if there was ever a time to do it, the year 2000 was it. So here we are."

And here it is: a revue entitled Des and Rosie Ride Again, which will open at HQ at the Hot Press Irish Music Hall of Fame in Dublin's Abbey Street next Tuesday. The modus operandi remains the same, with Keogh and Fergus Linehan producing the script, Rosaleen Linehan composing the music ("and of course I woggle the lyrics here and there as I go along") and "Professor" Peter O'Brien taking charge of the arrangements. "As in the old days - oops - as before," Keogh corrects himself, "we have a terrific musical quartet". Along with O'Brien on piano, this consists of guitarist Des ("between Riverdances") Moore, percussionist Johnny Christopher and a Croatian bassist by the name of Sven Buick.

A fair few bucketloads of water have passed beneath the comedy bridge since 1985, however. Those were the days before Irish stand-up comedians were drop-dead fashionable, before expletives could be left undeleted - before Father Ted, even. "There's no way we can pretend we're part of that change," says Rosaleen Linehan, "and we're not going to try. We're just going to do our own thing in our own way, and see how it fares. In the old days the shows were considered very savage. I hated the savage bits, and loved the funny bits. This time around we have one or two tough ones, and that's it.

"And we've revived the characters of Ita and Netta, the two oul' wans who gossip and comment on everything, and frequently get everything upside down, because they're perfect vehicles for this kind of comedy, and act as foils for each other - I'm quite outrageous, whereas Des's character is slightly politer. But, you know, as you get older - well, once I was in my 40s it really did matter to me which washing powder washed whiter, if you see what I mean."

Washing powder aside there's no shortage of raw material in contemporary Ireland. On the contrary, says Keogh, all those scandals, financial, political, ecclesiastical, have simply been going to waste, and the revue won't be afraid to tackle them head-on. But gently? "We're not going to be like the stand-up comics who talk about their private functions, that's for sure," he says. "Oh, dear, that sounds a bit dull, doesn't it? We want to have fun, but I wouldn't want to make anybody uncomfortable, and there are certain subjects I wouldn't touch because I feel it's unfair."

What will be totally new will be the cabaret atmosphere of the HQ venue - considerably more laid back than the Eblana Theatre, where it all began. Or did it? Fergus Linehan says he can't remember. "But I remember that the first thing I ever wrote in my life, I wrote for Des; a number called Do Join The Hockey Club, Do. For his idiot persona."

"And the first two-hander Des and Rosaleen did," recalls "Professor" Peter O'Brien, "was in 1976. It was called Two For Joy. Superb lighting - and I did a jazzed-up Mozart symphony, which was so hard that Des Moore and I had to go in and rehearse it every single night for the whole of the 12-week run. I'd love to do that again some time." But not this time, though O'Brien has written one of the 12 songs on offer - as has another Linehan, Conor, son of Fergus and Rosaleen and a professional pianist himself. "It's all he's interested in," calls Rosaleen from the other side of the room. "He met somebody connected to the show last week, and all he said was, `so how's my song going?'"

Which reminds Fergus of a story they used to tell about Cole Porter, stuck for a word to fill the line "a trip to the moon on [blankety-blank] wings". "He was sitting somewhat morosely in a bar and this guy asked him what was the matter, and he told him, and right away the guy said, `a trip to the moon on gossamer wings'. And every time Porter went into the bar after that, the guy would say, `hey, how's our song coming along?'" Which reminds everybody. "From the top, ladies and gentlemen - let's go."

Des And Rosie Ride Again will play in HQ at the Hot Press Irish Music Hall of Fame from January 18th