I am sitting in the Coronation Street Rovers Return pub on a Sunday afternoon, having a gin and tonic with Peter Barlow. This is a momentous occasion for me. Not a lot of people get to sit in the Rovers, and even if they do, I am assured that not many get served a real gin and tonic: the actors get fizzy water.

Being asked to be on Coronation Street is a flattering and terrifying proposition, especially if you have lived in England for any length of time, for it is as much a national institution as the queen.

In my case, having only been asked as the less famous partner of Shane MacGowan is less flattering but just as terrifying. The director tells me that the show (the longest-running soap on British telly) attracts about 10 million viewers per episode, 53 years after it was first broadcast in 1960.

However snobbish you are about soaps (and I am the first to admit I am snobbish about soaps. I generally restrict my viewing to Mastermind and edifying documentaries), that is serious exposure. Maybe if I make the right impression, I will be offered a permanent role. It could be the defining moment of my career. And because I don't have any lines to say, everything will hinge on what I am wearing.

Shane suggests I should go totally trashy – a bit Bet Lynch. I consider it, but in the end I am too shy, and opt for a demure and respectable look.

Favourite Christmas song
I should explain exactly how and why it is that Shane and I are now sharing pork scratchings with Peter Barlow. It is very simple. Shane's song Fairytale of New York was last year voted Britain's favourite Christmas song on ITV. The song has made the transition from being synonymous with Christmas in real life to being also a part of the Christmases of fictional characters such as the inhabitants of Weatherfield, where Coronation Street is situated.

Every year ITV hosts a charity fund-raising show called Text Santa, and as a part of this year's show, the cast of Coronation Street have created a special episode, Fairytale of Weatherfield, built around the song. That is as much as I am permitted to reveal at this point; the rest you will have to find out by watching the programme on Friday.

In the meantime, I can only say that Shane and I, along with our dear friend Gerry O’Boyle, are being filmed on location in the Rovers.

The Corrie community
When you tell people you are going to be on Corrie, it is quite surprising the type of person who is impressed. I am not suggesting there is anything wrong with Coronation Street, it is just that I have not got into the habit of watching it. And perhaps I had formed a prejudice about the type of person who might watch it.

But my prejudices have been obliterated by this experience. Shane's mother, for example, is a sophisticated, exceptionally intelligent woman, from whom he inherited at least half of his genius. And yet she tells me she was thrilled to bits when she heard that her son is going to be on Coronation Street. She has not missed an episode since the series began, she tells me.

I am also mystified when very posh people tell me they watch it. My sister Joanna is the châtelaine of Hilton Park House in Co Monaghan. It is the type of house where they have custom-made top hats from London's Jermyn Street sitting unworn in their boxes, and yet her in-laws practically fainted when I told them my news.

Perhaps the strangest revelation was Gerry O'Boyle himself, who was the one who introduced us to the director and accompanied us to the Rovers Return. Gerry is the pub landlord equivalent of Natalie Barney or Gertrude Stein, having hosted such eminent authors as Pat McCabe, Edna O'Brien and Nick Cave, among many others, at his legendary Vox'n'Roll events over the years. And yet, his specialist subject is Coronation Street.

His knowledge of the ancestry of the characters is so vast as to cause the director to look rather worried, when he casually mentions Peter Barlow’s great grandfather and what he would be thinking.

As we arrive at the set, Chris Gascoyne, who plays Peter Barlow, is waiting outside, along with Matt Hilton, an assistant director on the show. Gascoyne is wearing a fetching hat, which he later gives to Shane as a present.We are taken on a tour through the streets, which look exactly like real streets. You can touch the buildings and they won’t fall down. Shane waits patiently in the pub while the rest of us have our pictures taken at every shop and house.

In the newsagent window are handwritten signs for things such as babysitters and tarot readers. “Those get changed regularly,” Matt tells me. Someone actually has the job of making up those signs. In the sweet shop, the sweets are real, but very, very old. “You wouldn’t want to eat them,” he tells me. Although I am not so sure.

Christmas decorations
The bar looks like a real bar. Shane thinks it looks slightly smaller in real life, but I think it looks about right. They have the Christmas decorations up, which makes it warm and cosy. Later on I steal them and stuff them in my bag.

We are joined for drinks by Matt’s parents; his dad, Paul, is an undertaker in real life, but he also gets to be the undertaker in the show whenever anyone dies. Matt’s mum also gets to be in the show. It seems anyone who hangs around long enough can get to be in the show, which bodes well.

The Corrie world is a community unto itself, with the actors and crew lodging with other actors and crew. Everyone seems unnaturally happy. Do they ever fight? I ask one of the cameramen. "Sometimes we do, but not for long. We are together most of the time, so we couldn't fight for long."

“Hmmmm,” I say, unconvinced.

Matt’s undertaker dad starts telling us how he used to be a baker and only became an undertaker after answering an ad in a paper looking for people who wanted to totally change their lives. He always liked the idea of dead people, he tells us.

As he tells the story, we forget we are in a fictional pub, and we sink into the cosiness of this little community of real people sitting together, having a drink and sharing stories. Which is what pubs are supposed to be about – although at home we hardly ever go to pubs.

Maybe that's what compels so many people to watch Coronation Street: for a chance to hang out and share in other people's stories, be they real or not. The chance for a sense of community.

Text Santa is on UTV on Friday at 8pm


MACGOWAN ON THE MAKING OF 'FAIRYTALE': 'NEW YORK IS A NASTY PLACE TO GROW OLD'

"I'm very grateful to Christ and his Holy Mother and Joseph and all the saints, including my family who have passed on, for the success of Fairytale. And I was very grateful to Kirsty MacColl. I don't think it would have been such a big hit without her contribution.

“And of course I was grateful to the group, it was a very happy time for us when the song came out. It’s a good song – it’s a great song – I’d never get tired of it. But I just can’t really get excited about it any more, and for a while it used to depress me to sing it after Kirsty died, but now I just think of it as a tribute to her.

“The title came from the JP Donleavy novel A Fairytale Of New York.

"Jem [Finer, of the Pogues] was reading it at the time. Elvis Costello liked the lyrics, particularly the bit about Christmas Eve in the drunk tank. So he said 'Why don't you call it Christmas Day in the Drunk Tank?'

“ I said: ‘what a ridiculous idea!’ Everybody just burst out laughing. Then I glanced at the book, and it had come into my head a couple of times before to call it after the book. So I said: ‘let’s call it Fairytale of New York.’

“In the song, the couple go to Broadway, because Broadway was where you made it in New York, if you were a singer. But really, the story could apply to any couple with big dreams who found themselves down on their luck. You don’t know what is going to happen to the couple, the ending is completely open.

“I think the story is one that has not really changed for the new generation of Irish people emigrating to New York. It’s still a nasty place to grow old. It is a novelty at first, but in the end it’s a very tough place.”