Why It's A Wonderful Life is the nation's favourite

The film poster for It's A Wonderful Life

It's been voted Britain's favourite Christmas film, but there will be a lot of people who have never watched It's A Wonderful Life.

The film is over 70 years old and is an uplifting story of family, love and hope.

But it is also the story of one man's struggle with life's knockbacks.

In fact, what people forget is that despite the title, the main character's life isn't that wonderful.

"It deals with the desire to take one's own life and also what happens when there is a big financial pressure on you," says Radio 1 film critic Ali Plumb.

"When I rewatch it, I keep thinking there is so much more depth to this movie than (famous scenes like) lassoing the moon or the dancing in a big hall."

Frank Capra's 1946 film featuring James Stewart is a regular fixture on TV across the Christmas period, beaming an uplifting story of family, love, hope and redemption into our living rooms.

And that's another reason it's become so popular: it has been around long enough to reach several generations.

Although the main character, George Bailey, goes through a crisis, he's reminded about the importance of family, love and friendship.

Another reason why the film is so iconic: it's one of the first films to highlight male mental health.

That's one of the reasons why part of the script have been painted on train platforms from London to Glasgow.

It"s A Wonderful Life was painted onto a railway station platform at Glasgow Central as part of a mental health festive campaign

More than 7.5km of words from the film have been painted along the yellow line at 14 stations across the UK.

Virgin Trains have teamed up with mental health charity Rethink to raise awareness about how the festive period can be difficult for some, and the positive impact that simple acts of kindness can have.

Rethink's James Fletcher says that the film's timeless message of helping each means that it's the perfect film to paint on platforms.

"It's the fact that it's so loved and tackles those tough issues. We can use that message to encourage people along the West Coast network to carry out acts of kindness at Christmas and throughout the year," he explains to Newsbeat.

"The film is so powerful because George Bailey is so busy all the time and people don't get the chance to show him how much they appreciate him. That relates to all of our daily lives, some 70 years later. We're all incredibly busy and we still need the odd nudge to look out for people and let them know that we're there."

James also says that the film's message of kindness has also stood the test of time.

"What's incredible is the way that it's endured and that message of kindness has struck people and stayed with them.

"It links back to Charles Dickens and A Christmas Carol - the idea of what might happen if you're not around."

But does it deserve to be Britain's favourite Christmas film?

"Absolutely, it's a timeless classic that people can just get drawn into," says James.

"It has that sad and difficult story, but ultimately it leaves you with a smile on your face at the end as well."

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