Phil is dispatched to the folksy town of Punxsutawney,Pennsylvania,to cover the annual February 2 celebrations,which revolve around a groundhog supposedly foreseeing the exact date of the arrival of spring.

"This is one occasion where television really fails to capture the true excitement of a large squirrel predicting the weather,"Phil sneers to camera. But when he wakes the following morning,it is February 2 again. And February 2 it will remain indefinitely,rebooted each day at 6am,until Phil can figure out how to arrest the cycle. The secret,it transpires,lies within him.

The film's timelessness can be attributed partly to its classical redemptive narrative,which has echoes ofA Christmas Carol."The redemption plot is one of the oldest story shapes,"says Peter Baynham,a writer whose script credits includeBorat,Arthur Christmas and the forthcomingAlan Partridge:The Movie.

"With so many movies,especially comedies,you can see the bones sticking out – you can see what they're trying to do. ButGroundhog Day is such a clever,wonderful ride that you don't notice the joins. It's rare for a comedy to be funny and profound but also popular.

"Films such asGroundhog Day andBack to the Future sold a lot of popcorn,but they were insanely smart too. That's very inspiring when you're sitting there trying to write a comedy screenplay.Groundhog Day is living proof that it's possible to create intelligent comedy that still has a broad appeal."

Also remarkable is the film's refusal to reveal how Phil came to be stuck in his time-loop:there is no magical fairground machine (Big),no mantra (Shallow Hal),no curse (What Women Want). Nor does it specify the amount of times he repeats the same day. It could be 10 years or a 1000,however long it takes him to memorise the personal histories of Punxsutawney's townsfolk,and to become,among other things,a pianist,an ice-sculptor and a doctor ("It's kind of an honorary title,"he shrugs). That radical withholding of information makes it something of an art film in mainstream clothing.

The artist and filmmaker Gillian Wearing includedGroundhog Day in her all-time top 10 when polled last year bySight&Sound magazine. Her list included other enigmatic,if less multiplex-friendly,films -L'avventura,The Exterminating Angel,Last Year at Marienbad.

"All those films reinvent structure and create a new conceptual framework that makes you understand them,"Wearing says."They share an almost surrealistic vision,and they pose philosophical questions.Groundhog Day is there primarily to entertain,but there are lots of really intelligent ideas in it. It makes me think of[the French philosopher Gilles] Deleuze and his thoughts on how change can arise from repetition. The film follows that to the letter."

Not that the studio pushed the screenwriter Danny Rubin to go big on Deleuze or to make the third act more Marienbad-ish. On the contrary,Rubin was urged to write a gypsy-curse scene explaining the loop,which Ramis wisely never shot.

The mystery has only fortified the film's magic. Its chances of longevity were helped,too,by a purge on period references. Rubin urged Ramis,with whom he shares a writing credit,to expunge any nods to the 1990s:"You've gotta take all this out,"he said,"because this movie is really going to go on for years and years."

Speak to any of the film's admirers and one word comes up repeatedly:perfect."I thought straightaway that it was a classic,"Wearing says."It's like a Billy Wilder film:other generations will understand immediately what's so good about it. To me,it's a perfect film."

Russell agrees:"It's perfect in its structure,and its ideas are so profound. Very much likeSilver Linings Playbook,it's about someone fighting their demons using all that humble,difficult,baby-steps hard work that it takes,but doing it in such a hilarious way. It shows that until you wake up and get things right,you're going to live that stuff until you die:the same emotional prison every day. Phil has to go through every incarnation of what he thinks love is until he really gets it."

Like Russell and Wearing,the former Monty Python member Terry Jones also includesGroundhog Day in his top 10."What's so remarkable about it,is that normally when you're writing a screenplay you try to avoid repetition. And that's the whole thing here,it's built on repetition. That's so bold. The way they get through it is to short-circuit everything,so just when you think something is going to happen that you've seen before,the film gets to it before you and changes or abbreviates it in some way. I saw it when it came out and it just took my breath away."

It still does. I watched the film again at a London cinema last weekend (onGroundhog Day itself,in fact),where it played to a rapturous soldout crowd who hung on Murray's every poisonous put-down. ("Probably the best work that I've done,"Murray once said of the movie.) His performances since then,from his collaborations with Wes Anderson (including last year'sMoonrise Kingdom) to his Oscar-nominated turn in Sofia Coppola'sLost in Translation,each have as their springboardGroundhog Day. Before that,Murray was seen largely as a clown. After it,he was a complex actor with range.

"It's the movie he was born to make,"Russell enthuses."It's his greatest role. His cynicism and eventually his sincerity feel so real because he comes by them so honestly. He proves that if you feel it from the feet up,there are no cliches."

If the impact ofGroundhog Day is still felt on Murray's career,its influence on cinema in general is ever more prevalent. It legitimised fantasy aspects in mainstream comedy so effectively that stars such as Jim Carrey (inThe Truman Show,Liar LiarandBruce Almighty) and Adam Sandler (inClickand50 First Dates) spent years trying to replicate its formula.

Its imprint can be detected on films as diverse asSliding Doors,The Family Man,Run Lola Runand the recentSafety Not Guaranteed. In 2004,there was an Italian remake,though the best thing about that was the title:E gia ieri,orIt's Already Yes-terday.

Later this year,Richard Curtis will try for theGroundhog Day effect withAbout Time,featuring a hero who can zip back and forth through episodes in his own life. In one sequence,he refines repeatedly his first night with a new girlfriend until he perfects his technique. Phil Connors,never shy of using supernatural subterfuge for sex,would have approved.

"There have been a lot of messing-with-time movies where you can't help but see the influence of Groundhog Day,"Rubin says."There wasSource Code,which was likeGroundhog Day but with a bomb on a train. I quite liked that. Every time it happens,my friends say:'You just got ripped off. I hope they paid you.'I'm,like:'No,it's a homage.'It's not like I'm being erased. It's an honour.

"I always thought the premise could be explored a million different ways. I welcome all of these explorations;it's fun for me because I like to see how other people play with the idea.

"Basically it shows how ubiquitous it's become in the culture. It's getting harder and harder now to find anyone who hasn't seen it."

GUARDIAN