Joanna Lumley felt a deep connection with Elvis Presley as a teenager - and says if she had met him, they would "obviously" have married.
The actress went on a tour of Elvis's haunts and interviewed the singer's former wife Priscilla for the filming of Elvis And Me, which focuses on his rise to fame and the early years of his success.
Lumley, 69, became a fan of Elvis, who would have been 80 this year, when she was a child.
She said: "I felt if I'd met him, I'd have obviously married him. And the fact that Priscilla was gorgeous when she was 14, and I was a spotty nerd, was beside the point. Everybody in the world felt: if I'd met Elvis, I would have been his best friend, girlfriend. Everybody."
On interviewing Priscilla, who met Elvis at the age of 14 and married him at 21, Lumley said: "I loved her. She was extraordinarily generous, very open.
"It's a long time since Elvis has died, and she's been asked everything about Elvis, everything's been written about Elvis good or bad. The adoration is such that is like practically a kind of religion, the love of Elvis.
"And she's steadfastly had to endure that and make herself strong enough to cope with it. She in her own right is a terrific person, but of course, we only really see her as the Elvis bit."
She added: "He's been my number one for ever and a day ... Elvis was always singing to me. Obviously. And even Priscilla, when she wrote a sweet letter after we'd shown the film to her, put: 'It was such a pleasure to show Joanna around Graceland, the house which ought to have been hers' - with a smiley face."
The documentary focuses on the early years of Elvis's life before his divorce, weight gain, heavy medication use, health deterioration and death in 1977.
This was a deliberate choice by Lumley, who said: "I didn't want to do the end of it. I'm not interested in that. I hate studying bad things.
"Too much of our life is going: 'Oh, but look what happened'. That was the aberration at the end of his life, when the doctors had got hold of him, prescribing all kinds of ghastly pills, when life had got hold of him. He was only 42 but nevertheless fame had eclipsed him and it became harder and harder to be alive.
"I don't want to do that, because that's not the Elvis the world loves. The world loves the boy who sang Blue Suede Shoes, or Jailhouse Rock, who hung around with his great big gang, who was very polite and called interviewers 'Sir'. There was something touching, and I just wanted to know: how do you get to be there? How did this boy come? Was he born like that? Was he made like that? Influenced to be like that?"
In the hour-long documentary, she visits Abbey Road to watch a recording session of the new Elvis album If I Can Dream with the Royal Philharmonic Orchestra, who are re-doing the backing music to many of his most famous songs.
She also makes a trip to Tupelo, Mississippi - Elvis's home town - where she visits the shack where he was born and the hardware shop where he bought his first guitar.
She also talks to some of the people who knew him, including Sam Bell, who reveals what life was like for a young Elvis growing up in a time of segregation.
Lumley said: "There was something about Tupelo, that I felt him. There was something about the boy there in the hardware shop, and the guitar was there, and you get a feeling going - oh he was only a little kid and this was - it's still a hardware shop.
"I felt him in the cinema with Sam. Black friend Sam, in the cinema, from his childhood, when they would have to go through separate entrances to the cinema, and Elvis would duck under the rope and sit with them. And I loved him for that, because he was only a little boy, and he was colour blind. He didn't get that, while the country got that, Elvis didn't get that. And sitting in that little cinema, exactly where they sat - that was something."
She added: "I feel Elvis and I have always known each other. What I mean is that I found I'd got a bit nearer to him, but there's something un-knowable about him I think, too."
Looking back on hearing news of Elvis's death, she recalled: "I was in Canada. We were filming The New Avengers, we were doing some episodes up in Toronto, and it was absolutely ghastly. It was just ghastly.
"From the British people there was only Patrick Macnee, Gareth Hunt and me there. And all the rest were Canadians. And Canadians were pretty sort of - 'pfft! So what?' about Elvis at that stage of his life, because everyone was just going: 'Oh, what a shame, he's so fat, and who cares.' So that was awful, not to have proper reverence due, you know?"
Lumley has also filmed documentaries about pop star will.i.am, the Trans-Siberian railway, and the Northern Lights - but now she is working on Absolutely Fabulous: The Movie, due out in 2016.
On reprising her role as Patsy Stone alongside Jennifer Saunders' Edina Monsoon, she said: "You only have to remember a few things. You just have to remember the body language because she's had all her organs taken out. You just remember that she wears hard - she wears hard red lips and things. She doesn't want anybody inside.
"And also she's beginning to lose it, because she's literally drunk so much and smoked so much and done so much. But this show, I tell you this film is funny. You're going to be very pleasantly surprised."
:: Elvis And Me airs on Wednesday at 9:00pm on ITV.