The story is now well-known among admirers of the Beatles: John Lennon's four-year-old son Julian presents his father with a painting at the school gates.

When asked what the painting is of, Julian answers: "It's Lucy, in the sky, with diamonds."

So began the creative process which produced one of the Fab Four's most charismatic hits, despite reports to the contrary saying it was Peter Cook's daughter Lucy who inspired the song.

The real Lucy is Lucy Vodden - a playmate of Julian's when he was at nursery school in Weybridge.

She now lives in Surbiton and, on the 40th anniversary of the famed Beatles album Sergeant Pepper's Lonely Hearts Club Band, has emerged once again as the inspiration behind the song.

She said: "I remember running around Julian's garden in St George's Hill.

"He had a swimming pool with beautiful tiles. I was always a bit scared of John as he was a big man with a loud voice, and I remember thinking Julian's mum was really glamorous - she used to pick him up for school wearing a mini-skirt and a beehive," she recalls as she sifts through numerous newspaper cuttings about her and "her" song.

But interviews are getting harder for Lucy, 44, because three years ago she was diagnosed with Lupus - on top of her existing conditions of psoriasis and arthritis.

"This isn't the life I imagined," she says of her daily dose of pain and fatigue.

She has given up work as an agent for disabled children's care, and has to spend most of her days away from sunlight in her Surbiton cottage while being visited by carers.

But she is grateful to have the support of her family.

She remarks: "It has been very difficult for my husband, because we can't have children.

"My previous boyfriend dumped me when I found out I had psoriasis, but Ross is my childhood sweetheart - we went out when we were 16 - and he has stood by me. I am very lucky."

At their wedding 11 years ago, a message of goodwill was faxed to her.

"It was read out by the best man, who allowed a pregnant silence to set in between reading from Julian', and Lennon'."

Julian too is the inspiration behind a track by the Beatles. Paul McCartney wrote Hey Jude for him when his parents were in the process of splitting up.

Lovely Rita now refuses to do press interviews, and Lucy counts Melanie Coe - about whom She's Leaving Home was written - as one of her friends.

She said: "I am safe in the knowledge that the song was about me.

"There was a theory that the other Lucy was the inspiration, and when she died sadly, my family received all sorts of condolences."

This was particularly upsetting given the circumstances of Lucy's health.

Despite the disease, Lucy remains optimistic, and is positively glowing about the care she receives from the Lupus unit at St Thomas' Hospital.

She says that although she has not been lucky enough to go into remission a lot of people do and she keeps herself informed about the disease.

She says: "I was reading a book about Lupus in a bookshop and Lucy in the Sky with Diamonds came on.

"My husband came up and said to me, There goes your song'.

"That was the last time I heard it."

q Go to to find out about PAA - the psoriasis and arthritis charity which supports Lucy.

For more information about St Thomas' Lupus Trust click here.