Originally released in 2006, the lovestruck ballad never reached number one in the UK, but remained on the charts for more than three years.

It took up a similar residency on the airwaves, where it has become the most popular song of the last 20 years.

Second place went to Black Eyed Peas' I Gotta Feeling, while Pharrell's similarly upbeat Happy came third.

"It's unbelievable," Snow Patrol's Gary Lightbody told the BBC. "I'm not sure how that happened."

Asked to explain the Chasing Cars' appeal, he said: "It's an emotionally open song and it's a simple song. But it's also unabashedly a love song, and we don't really have any others.

"The way it unifies an audience is the thing I most cherish about it. It's a beautiful moment every time you play it."

The song was taken from Snow Patrol's fourth album, Eyes Open. It was the 14th biggest-selling single of 2006, and the last song played live on Top of the

Lightbody was presented with a special award marking the achievement on Tuesday by music licensing body PPL, which tracks all the music played on radio and television in the UK, as it marked its 85th anniversary.

Speaking to BBC News, Lightbody looked back on the creation of Chasing Cars in a wine-fuelled, all-night recording session.

I read that you'd written Chasing Cars in the garden of your producer's house. Is that right?

Yes, Jacknife Lee had a studio in the shed of his garden and we went down there with a couple of bottles of wine, and we wrote through the night.

In fact, we wrote 10 songs that night - and five of them ended up on Eyes Open, so that was pretty much half the album.

Normally when you listen back to the music you wrote after a few glasses of wine, you go, 'Ah well, better luck next time'. But that particular evening, [we] gathered a lot of good stuff.

So what was in the air that night?

I'm not sure. We were writing a Snow Patrol record, but we were also tasked with writing some songs for some other people - so that might have taken some pressure off. But by the next morning, none of those songs were going to anybody else, that's for sure!

Who might have recorded Chasing Cars if you hadn't kept it?

Oh, I'm not going to tell you that! That's not fair!

Lightbody received his award from PPL boss Peter Leathem on Tuesday night

Everyone knows the "If I just lay here" part. Had you written that lyric before the session?

No, it came spontaneously. The lyrics for that song all came that night. They just came out onto the page. And that's how I used to write - with just a flow. They would generally just sort of come out, and I wouldn't edit, for better or worse.

So with Chasing Cars, it was just what was happening at that moment in my life. I was in love. So it was a true, true representation of what was going on.

I guess that's the secret. It's real emotion, with no filter and no censorship.

Yeah, yeah, that's very well put. It was as spontaneous a song as I've ever written. There's very few that were written so quickly.

That's why trying to like follow up or trying to like recreate a hit like that is a fool's errand. It's just never going to work that way again, because it's just about the magic that's in the air, the environment, the mood that you're in that day. All the chemistry comes together in that moment, and it can't be recreated.

Let's look at the other songs in this chart... Chasing Cars beat I Gotta Feeling and Pharrell's Happy. What do you make of those songs?

I mean, it would seem that there's a pattern in there, and that pattern has nothing to do with Chasing Cars. They're very upbeat songs that are giving an audience permission to kind of jump up and down and be happy. Whereas Chasing Cars is a little bit more reflective. But it's good company to be in, because those songs have been absolutely dominant.

People always say that writing a hit Christmas song is like a retirement plan... So is this song your retirement plan?

No! I don't have a retirement plan. I never thought about retiring. I'm always going to be writing songs.