John Lewis unveiled its 2015 Christmas ad this morning in its usual tear-jerking style.

Man on the Moon tells the story of a touching connection between Lily, a little girl with a telescope, and an elderly man living, inexpicably, on the moon.

He resides in a small hut, occasionally walks over to sit on a bench and have a look at Earth — and then, at the point where mums across Britain reach for the Kleenex, he receives a Christmas gift from little Lily.

It's a telescope, and he manages find her house, zoom in to her window, and see his Secret Santa for the first time, as a solitary tear rolls down his cheek. It's almost too much.

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The advert, accompanied by a cover of Oasis track 'Half The World Away' by Norwegian singer Aurora Aksnes, throws up a few questions, however.

How is he alive, on the moon, wearing just a shirt and some trousers? Who built his little house? Which branch of B&Q delivered that bench?

But who is he? Here are five guesses:

Major Tom

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At the end of David Bowie's 1969 hit Space Oddity, Major Tom was floating round his 'tin can, far above the moon', with no hope of a return to Earth. Perhaps he managed to land his tin can, build himself a little house on the moon and has been hoping a passing rocket will pick him up ever since.

Santa

Santa in his grotto in the Victoria Tower, Castle Hill. Santa with Dion Silkstone,3, during his visit to Santa in the tower.

You can't tell us the bloke in the advert doesn't look a little bit like the Man in Red — he's got braces and everything! Perhaps his magical powers mean he can live quite comfortably in space. And think about it, with global warming, the moon's probably a safer bet for his HQ than the North Pole.

Rocket Man

Where did Rocket Man end up, Sir Elton?
Where did Rocket Man end up, Sir Elton?

So Elton John's Rocket Man went off to Mars, for 'a long long long time'. Well, perhaps, when he was finally able to leave the red planet, he decided he'd had enough of Earth life (after all, he sang "I'm not the man they think I am at home") and decided to set up shop on the moon.

The Doctor

Doctor Who (PETER CAPALDI)
Doctor Who (PETER CAPALDI)

Bear with us. Maybe, just maybe, Peter Capaldi is pretending to be Dr Who, as the real Dr Who got fed up with rescuing his companions from whatever drama they got caught up in each week and decided to just observe Earth from a safe distance. "You take over mate, I'm off to the moon to make hot chocolate and sit on this lovely bench I've ordered."

An Apollo 11 crew member who fell out with Buzz Aldrin

Apollo 11 astronaut Buzz Aldrin standing on moon, with astronaut Neil Armstrong & lunar module reflected in helmet visor, during historic 1st walk on lunar surface.
Apollo 11 astronaut Buzz Aldrin standing on moon, with astronaut Neil Armstrong & lunar module reflected in helmet visor, during historic 1st walk on lunar surface.

The reports say three men were on the Apollo 11 mission: Neil Armstrong, Buzz Aldrin, and Michael Collins. But what if there was a fourth man who got left on the moon and the whole thing was covered up by NASA? (Tin foil hats at the ready.) Perhaps he had a barney with Buzz Aldrin, and they refused to take him home. He might have nicked his rations or something. And he's had since 1969 to sit in his little house and think about what he did.

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Speculations aside, this year's John Lewis advert carries a powerful message about remembering those who may be alone this festive season.

John Lewis' tear-jerking Christmas ad
John Lewis' tear-jerking Christmas ad

John Lewis has partnered with Age UK to drive awareness and support for some of the million older people who can go for a month without speaking to anyone.

Craig Inglis, customer director at John Lewis, said: ""We hope it inspires people to find really special gifts for their loved ones and through our partnership with Age UK, raises awareness of the issue of loneliness amongst older people and encourages others to support in any way they can."