Media playback is unsupported on your device Media caption Take On Me, by A-Ha, entered the top 40 in the UK 25 years ago

The flickering, comic book-style animation of 1985 video Take On Me, by Norwegian trio A-ha, was a defining moment in the history of music promos.

Twenty-five years after the song entered the UK top 40, the combination of quirky video and insanely catchy song - driven by Magne Furuholmen's killer keyboard hook - remains the perfect pop package.

It was written after Furuholmen and guitarist Pal Waaktaar - of Norwegian band Bridges - invited dashing acquaintance Morten Harket to go to London to form a new group.

WHAT HAPPENED NEXT? A-ha's next video, The Sun Always Shines On TV, begins with a continuation of Take On Me

Morten Harket and model Bunty Bailey's love story comes to an end as he turns back into his animated self

A-ha won eight MTV VMAs in 1986 - six of them for Take On Me. The haul was matched by Lady Gaga this year

The Museum of Modern Art, in New York, has put the Take On Me video into its permanent collection

Animators Mike Patterson and Candace Reckinger went on to direct Suzanne Vega's Luka and Paula Abdul's Opposites Attract

Number two UK album, Hunting High and Low, featured hits Take On Me, The Sun Always Shines On TV, Train of Thought and the title track

Steve Barron, who directed films including Teenage Mutant Ninja Turtles, has made the promo for A-ha's new song, Butterfly Butterfly - his first pop video for 14 years. He made "about 120" in the 80s

They had yet to hear him sing.

"I went off with the other two to Pal's parents' house, we were still kids more or less, and in his room there was a shabby keyboard and a really bad acoustic guitar," remembers Harket, now 51.

"And I said, 'play me something, just let's start somewhere'.

"That riff of Magne's is the first thing I heard and I knew immediately that this was a big song."

That riff, coupled with Harket's falsetto plea to take him on, were to ultimately propel the first song they wrote together to number one in the US Billboard singles chart.

With a little help from that video.

The trio - who are to split after the release of a greatest hits album and a series of live dates - moved from Norway to London in January 1983, signing with Warner Bros in December.

But the release of a formative version of the song, complete with an early low-budget video, failed to chart.

They returned to the studio, this time with Barbara Dickson and Cliff Richard producer Alan Tarney, "and did Take On Me the way you know it".

Image caption A-ha, whose greatest hits album is out this week, will retire after a series of live dates. Credit Jason Joyce

"The rest is history," says Harket. "It was picked up by the Warners people in the US and they then introduced us to the video director, Steve Barron."

"Warners said they had these young good-looking guys from Norway with a good pop song and that they really believed in them," says Barron, whose CV included Ant Music, by Adam and the Ants, and Michael Jackson's Billie Jean.

He was given a big budget as well as a rare commodity in promo making - time.

"They said, 'we'll give you as long as you want and we'll release it when you've finished it'," says Barron, 54.

Fleeting style

Warner Bros in Los Angeles hooked him up with US animator Mike Patterson whose five-minute student film Commuter had made a big impression with label executives.

Media playback is unsupported on your device Media caption Extract from Commuter by Mike Patterson - the forerunner to Take On Me

It was made using the rotoscope technique - drawing over live action frame by frame - and featured the fleeting, black-and-white living comic book style that was to become Take On Me's calling card.

"Rotoscoping uses live action motion but my drawing style anyway was very loose and sketchy - no-one had really drawn anything like that style before," says Patterson, 53, now an animation lecturer at the University of Southern California.

"Rotoscope was usually done in a dry kind of way, very static or very sterile looking.

"But mine is more about just deriving the motion and creating a feeling of energy."

3,000 drawings

A concept was devised by Steve Barron, based on a comic book he read as a young child featuring "guys racing against each other on motorbikes and sidecars".

I knew that it was going to look good but I had no idea it was going to be in heavy rotation on MTV for a year Mike Patterson

A girl reading a comic book in a greasy spoon cafe - played by Bunty Bailey of dance troupe Hot Gossip - is attracted to a sketched version of Harket before she finds herself sucked into the animated world.

The pair are pursued by violent motorcyclists before the singer breaks out of the animation and the pair are finally reunited in the real world.

The band and actors were shot on film before the tapes were handed to Mike Patterson who, over 16 weeks, sketched some 3,000 drawings over individual frames.

"I knew that it was going to look good but I had no idea it was going to be in heavy rotation on MTV for a year," says Patterson, who worked on the video with wife Candace Reckinger.

US hit

The most memorable scenes feature Harket and the girl looking in and out of the real and animated worlds through a mirror.

Patterson, who was 28 when he worked on Take On Me, says the video was "partly responsible for the revival of experimentation in animation" while Barron says it was one of his proudest achievements.

I think it's quirky enough to be lasting because your other types of hit songs, in a way, fit so well. You get too used to them and you don't hear them anymore so they fade away Morten Harket

"Often in videos, you didn't really get to work an idea through properly and I knew with this one, because we were given full time, that we would really be able to do it," adds Barron.

Harket says the video was "unlike anything else and it gave the song the type of exposure that it needed".

"The video bought us time because the song was not an easy, immediate pop hit."

As Harket says, the song itself - with its simplistic chorus, synthesized drums and mock slap bass line - "has never been off American radios".

"I think it's quirky enough to be lasting because your other types of hit songs, in a way, fit so well," says Harket whose band are playing classic album Hunting High and Low in its entirety at London's Royal Albert Hall on Friday night.

"You get too used to them and you don't hear them anymore so they fade away."

Image caption Take On Me was on hit album Hunting High and Low

Despite the success of the video and sales of more than 500,000 copies in the UK, Take On Me sat at number two for three weeks behind The Power Of Love, by Jennifer Rush.

That the song only reached number one in the UK when it was covered by long-forgotten boy band A1, in 2000, is sacrilege.

So needless to say, it's the original video which remains a regular fixture of music video channels.

"What's crazy for me is that I have students who were born after the video and they say it was their favourite video," says Patterson, now 53.

"I can go anywhere on the earth, I've been in so many different continents, and wherever I go, everybody goes, 'I love that video'."

A-ha's greatest hits album, 25, is out now. The band are playing a series of live dates in Europe throughout the rest of the year.