The Xmas Factor: What is it like to be a one-season, one-hit wonder?

August 1994, at what was fast approaching the height of Walthamstow-boy-band East 17's commercial peak, chief songwriter Tony Mortimer, then 24, sat down to write a paean to his brother, Ollie, who had recently committed suicide.

The song was called "Stay Another Day" and featured the lyrics: "Don't you know we've come so far now / Just to go and try to throw it all away?" For a band who mostly vied for Take That's hormonal teenage audience, this was disconcerting territory indeed, the song uncomfortably, if necessarily, bleak.

"But then I played it to the record company who promptly decided it was a Christmas Number One," Mortimer says now, at home in Essex, and smiling at the memory. "I was like, a Christmas Number One? Do you mind? This is a really personal, sad song..."

But any offence he took was fleeting: "To be honest, I was just really happy somebody was saying the words 'Number One' to me. We'd had a lot of number twos, some number threes, but never a Number One."

When they went into the studio to record the single, their record company insisted on putting some church bells over its final mournful coda, which, the producers hoped, would be redolent not of death but rather chestnuts roasting on an open fire. "Stay Another Day" was Number One throughout December 1994, and into the first week of January 1995.

"And we simply couldn't cope with it," Mortimer says. "You know, the sheer size of it, the pressures that came with it. A Christmas Number One, and it contributed to our downfall. Ironic, eh?"

Shortly afterwards, prompted largely by Mortimer's repeated clashes with co-singer Brian Harvey, a man who always did have something of the Staffordshire Bull Terrier about him (and a man who, 11 years later, would somehow manage to drive his own car over his own head, very nearly killing himself), the band split. "Stay Another Day" would remain a fixture of the Christmas charts, haunting Mortimer with a version of himself he had never been much enamoured with in the first place.

"I've always thought of myself as musician first, if not poet," the 39-year-old muses. (If this sounds pretentious in black-and-white, it should be noted that Mortimer is uncommonly ruminative for a former pop star, more Zen and the Art of Motorcycle Maintenance than Heat magazine.) "I never wanted to be just a karaoke singer, to be honest with you."

But that was to be his enduring legacy, at least to date. East 17's sole UK Number One is now a staple of the British Christmas season, every bit as much as Slade's "Merry Christmas Everybody" and Wizzard's "I Wish It Could Be Christmas Every Day", and it continues to afford him, just as it does Slade and Wizzard, a very comfortable living. Perhaps mercifully, then, Mortimer has come to accept his fate.

"Actually, I like the song now more than I ever did then," he admits. "I suppose it's quite fun to suddenly become so much more recognisable in places like Homebase around December time. Friends call me up throughout the month to say they've just heard me in Asda, or on EastEnders." He laughs ruefully. "I'd love to say that I went out of my way to create this little slice of Christmas immortality, but I'm afraid I'm not that clever. It was more luck than judgement on my part. And anyway, 'Stay Another Day' is not a patch on Wham!'s 'Last Christmas' or Mud's 'Lonely This Christmas', is it? But I'm glad to be mentioned in the same breath. There's worse fates."

Christmas has long been a period of staggeringly crass commercialism and poor taste, with department stores convinced we will buy any old tat, even if it means going into debt in order to do so. The music industry treats us similarly, re-releasing all the old chestnuts on the (entirely correct) presumption, as Pet Shop Boys' Neil Tennant tells me, "that we suddenly feel the need to panic-buy them all over again, if only because it's Christmas, and if only because we always invariably do."

And so those hoary old classics come barrelling back at us. Collectively, we lose all sense of critical faculty, and welcome them with open arms – the more the merrier. At what other time of year, for example, would it even be permissible by law for Rolf Harris and Status Quo's Rick Parfitt to get together to record a seasonally dusted duet? That's just what they've done this year, with a song called "Christmas in the Sun", whose title alone suggests how they plan to spend the royalties if any of us are fool enough to buy it. And while Noddy Holder spreads himself throughout all media in a manner that frankly wouldn't be possible in either March or July, the band he no longer plays with, Slade, are busy touring again, just as Wizzard's Roy Wood is. What better way to top up the pension fund?

"It really is one of the most remarkable things about being a musician," agrees former Radio 1 DJ Mike Read, a man who looks remarkably like Shakin' Stevens these days, and is himself about to enter the Christmas singles market with a jokey jingle called "My Christmas Card To You". "A few minutes of music really can change a musician's life for ever."

He recounts the story of an old friend of his who wrote what turned out to be a one-hit wonder that performed well on both sides of the Atlantic several decades ago. "He still gets royalty cheques of somewhere in the region of £50,000 a year. It's difficult to get grumpy about being reminded of your former self when you're making that kind of money, no? It also means they'll never be forgotten."

Indeed. A classic Christmas single effectively renders its creator in aspic. Courtesy of "A Winter's Tale", then, David Essex will always be luxuriously coiffed; thanks to "Walking in the Air", Aled Jones will be 12 years old for all eternity; and even Paul McCartney, that former Beatle, will for ever have one foot stranded on Kintyre, the other squashing a burping frog mid-chorus.

One would imagine this brings comfort to any artist. Who doesn't, after all, crave immortality? Yet there are some who wish we would just shut up about the past.

Shakin' Stevens, a man responsible for 30 million record sales around the world, remains a pro-active recording artist to this very day. Not many people know this, but he has a strong following in places like Denmark and Poland. But in the UK, the man who once curled his lip like a boy-Elvis Presley, only really re-enters national consciousness during this month, when his "Merry Christmas Everyone", a song with all the preternatural fizz of an advertising jingle, climbs indefatigably back up the charts. In the past two years, on download sales alone, it has been comfortably nestled inside the Top 20 by the time the turkey is ready for carving.

We meet in a Soho hotel during a rare promotional trip to the capital. Stevens, 61 years old now, looks as much like Mike Read as Mike Read does him, his eyes hiding behind a pair of blue-tinted glasses, fluffy hair as black as coal. I ask him whether, like so many festive favourites, he feels more recognisable in December. He frowns.

"What? Why? Am I any less recognisable to you now in late November?" he says. (We meet at the very end of that month.) "No. Well, then. Strange question."

He would much rather talk about the imminent release of his Epic Masters boxset – featuring 147 Shaky songs (his Christmas classic conspicuous by its absence) – insisting that nostalgia is something he leaves to others. "I still feel I have so much more to give, you see," he stresses.

The British public, however, might just feel otherwise. When we do get back to the subject of his Christmas hit, he reveals that it was initially due for release in 1984, but he decided to hold it over for a year because he didn't want to challenge Band Aid's "Do They Know It's Christmas?" for the Number One spot. "You don't deny charity, do you?" Instead, he denied charity a year later when "Merry Christmas Everyone" held a returning Band Aid off the glory spot. "Well, I always did want a Christmas Number One. I got it."

He says that he mostly turns down the opportunity to re-promote the song every year, though he did do just that on Rob Brydon's Christmas chat show a couple of years ago, and TV's Dancing on Ice last year. But to discuss a song now 25 years old, he suggests, is pointless. It's all been said and done already, while the future lies tantalisingly before him.

"Trouble is, until we get another hit album, people will still just have that same old preconception of me. But I've changed, I've moved on. I have." His jaw sets in what appears to be irrevocable frustration.

Moving on is not something you could ever accuse the Pogues of. Every year, this most jubilant of Irish acts return with all the reliability of that Christmas card from a distant aunt. "Fairytale of New York" was an exquisitely bleak seasonal song that revolved around Shane MacGowan and the late Kirsty MacColl's drunken lovers' spat. It was a huge hit when first released in 1987, and has re-entered the charts almost every year since.

"It's certainly done very well for itself," grins the band's co-founder Spider Stacy. "I'm sure there are lots of people that only know that one song of ours and have never bothered to take their interest any further, but there have been just as many who have used it as an introduction to us, and have been faithful ever since."

The band is, Stacy insists, blissfully untroubled by the fact that it has overshadowed everything else they've ever done. "When a song of yours enters that kind of sphere," he says, "alongside classics like John Lennon's 'Happy Christmas (War Is Over)', you have to accept that it will take you places you never imagined reaching. I know for a fact, for example, that it will be heard on Hollyoaks on 18 December." This fact, gleaned from a friend who writes for the show, slaps a grin on Stacy's face that suggests nothing in life could be sweeter.

Its enduring popularity, meanwhile, has even tempted MacGowan back to the fold (he quit the band, or was possibly fired, back in 1991). For nine years now, they have reformed for an annual festive jaunt around the UK, before heading over to America for St Patrick's Day in March. They know their strengths, the Pogues, and are happy to play exclusively to them.

"I suppose we could always write new material," Stacy muses, "but it's been 20 years since Shane left, and so if we did write new stuff, it very likely wouldn't sound anything like our old stuff, which is what our audience expect from us. To be honest, we're quite happy giving them what they want, nothing more."

If there has been something of a lack of decent Christmas singles these past few years, then we can perhaps lay blame with Simon Cowell, whose X Factor hopefuls exert such a stranglehold over the charts' higher echelons throughout the month of December that it effectively renders all other hopeful big-hitters redundant.

But Neil Tennant thinks it might be a ripe year for at least one of those non-X Factor hopefuls. No, not for Rick & Rolf's tune, but rather for the Pet Shop Boys'. It's called "It Doesn't Often Snow at Christmas", and is a quintessentially Pet Shop Boys composition: wry, deadpan and so very arch that it almost bends right back on itself. Though it may feature sleighbells and, at one point, a very tight-trousered choir, it also dares to tell Christmas as it really is: riven by familial disharmony, too much food and rubbish on the television.

"That's true," Tennant smiles tartly, "but it also does contain, I hope, a very uplifting melody. I actually hope it will appear on Christmas compilations for ever now. I think it's a really good song, and I think, like all great Christmas songs, it contributes to the warm feeling that exists despite all the commercialism and excess at this time of year."

He's right, of course. It does. All great festive songs do, which is why they flourish year after year after year. They lift our spirits just as they do the fortunes of those pop stars who otherwise would only exist as questions in Trivial Pursuit. So while Christmas may well be about turkey and baubles and returning unwanted presents on Boxing Day, it's also about Jona Lewie's "Stop The Cavalry", Greg Lake's "I Believe in Father Christmas", and – yes, yes – even Cliff Richard's "Mistletoe and Wine".

Shakin' Stevens 'Epic Masters' boxset, Mike Read's 'My Christmas Card to You' and Pet Shop Boys' 'It Doesn't Often Snow at Christmas' are all out now. The Pogues are touring the UK until 19 December