"Happy Christmas your arse, I pray God it's our last".

Lyrics like the above do not, generally speaking, scream "yuletide cheer". Indeed, they don't sound like they could come from one of the most beloved Christmas songs of all-time; and yet, of course, Fairytale Of New York is precisely that.

Though that particular line is humorous, the song as a whole goes beyond mere comic caricatures. There is a melancholy to The Pogues' 1987 hit that has given it a timelessness. At any other time of year its huge popularity wouldn't seem so incongruous: to paraphrase 'High Fidelity', pop music is generally miserable, and that's why we love it. But why, around The Most Wonderful Time Of The Year™, are we so drawn to such an overwhelmingly sad song?

Of course, it's no coincidence that the original version of Have Yourself A Merry Little Christmas had the grim line "Have yourself a merry little Christmas / It may be your last / Next year we may all be living in the past". Think of Last Christmas, 2000 Miles, even A Spaceman Came Travelling - there is something inherently sorrowful about a lot of our favourite Christmas songs. Of all of them, though, it is Fairytale especially that seems to resonate.

As you are probably aware, the song (which took over two years to write) details the story of a man reminiscing in a drunk tank on Christmas Eve. It's a tale of romance turned into resent - the gritty lovers' quarrel after moving abroad, struggling to live up to the lofty dreams of their younger selves. Life isn't as glamorous as they'd hoped, and they've gone from kisses on street corners to rows and disturbing substance abuse - "You're an old slut on junk, lying there almost dead on a drip in that bed". It's not exactly Bing Crosby.

Part of the song's appeal might be in striking a chord with anyone who has found themselves in that specific situation: abroad with their partner and full of a cloying sense of bitterness. But, on a more universal level, the situation ringing true for so many of us might be more to do with that end of year sentiment of taking stock of one's life around Christmas: a frustrating sense of failure in not ending up where you had hoped.

That classic Christmas film It's A Wonderful Life deals with a similar theme is telling: protagonist George looks back on his life and considers himself worthless, and thus intends to kill himself on Christmas Eve. He is thankfully visited by a guardian angel, who makes him reconsider his perspective, and helps George to realise the happy difference he has made to the people around him's lives. At a time of year where everyone is supposed to be happy, with the arbitrary ending of a year closing in, it is easy to become isolated in feelings of frustration and blueness, or indeed, for those with some form of depression to feel their symptoms exacerbate.

While Fairytale's swirling folky music is glorious and cinematic, while Kirsty Maccoll's vocal harmonies are nothing short of incredible, it is - of course - the lyrics that truly resonate:

"I could have been someone.
Well so could anyone.
You took my dreams from me,
When I first found you.
I kept them with me babe
I put them with my own
Can't make it all alone
I've built my dreams around you" 

It's that particular exchange in Fairytale that hits home with so many of us, because it is a reminder that you're not alone in the sentiment of feeling a bit lost and down around Christmas time. Indeed, for the surreal nature of stories surrounding Shane MacGowan (especially with that bizarre documentary about his new teeth), it's easy to forget what a lyrical genius he can be. Fairytale is an antidote to all the sugary, happy, festive schmaltz that seems to drone on for the best part of December. The song gives an open ending - we don't know if the couple reconciled - but it's important that it gives us a reassuring sense of hope.

Christmas is very much a nostalgic time of year, bringing us back to childhood and times we recall as being more carefree, and a lot of people still revel in the yuletide fun. It's great to be part of that all - tinsel, mulled wine, fairy lights, wonderfully gratuitous consumption of mince pies. But, just as much, it's a time of year where people are forced together in what can be tense, uncomfortable circumstances with too much heavy food and alcohol. Moreover, people can be homesick, lost, or just a little blue, wanting the Christmas experience that everyone on social media seems to be having.

It's why, almost thirty years since its release, Fairytale of New York, remains the unlikely festive favourite, in spite of - in many ways - having always been the underdog. For all the "sluts" and "faggots", and romantic interpretation about what New York in the 1940s might have been like, it's still about the realest Christmas song there is.