Her sister, Marion Billings, 59, has been married to Richard, an accountant, since she was 21. They have two daughters, Jo and Sophie, and live in Berkshire.

MARION: I've been told tales of how I reacted when Elaine was born — typical jealousy of the firstborn. Later, I was expected to take her out with me when I wanted to be with my friends. I resented the responsibility and she couldn't walk as quickly as we could — I felt she was in the way.

By modern standards, we had a lot of freedom to play away from home. Once, when Elaine was four, she came on her tricycle. But she hadn't learnt how to apply the brakes and slid down the bank into the pond. Luckily, it wasn't deep and a passer-by got her out. I took her home, dripping wet with muddy ankles, and got the stick for it. We were both sent to bed without any tea.

We always shared a bedroom, but not a life, because we were at different schools. I knew I wanted to go to secretarial college, but when Elaine left school she didn't have a set idea about a career. Dad, who was the least pushy of parents, suggested she might like to go to stage school. Elaine wasn't a show-off, but she seemed to live in a fantasy world. She would put on shows with her friend Heather, banging something to get the rhythm and playing with paper combs.

I didn't have any talent and sat on the sidelines watching. After she graduated from Ada Foster, Elaine's first job was modelling children's clothes at the Ideal Home Exhibition. When we saw her walking down the catwalk towards us, we grinned like cheshire cats.

I've always been conventional but Elaine experimented with different things. During her hippie stage, Mum said: "I'm embarrassed to be seen walking down the road with your sister." Looking back, she didn't wear anything extreme, just long skirts and dangly bits. At 21, I had a white wedding, and Elaine was my bridesmaid. I made her wear a turquoise satin dress, and I don't think she was too pleased about that.

My sister's in a profession that doesn't suit the life I chose as a wife and mother. It might be a regret that she doesn't have children of her own, but life's been good to her in other ways. She's a lovely auntie. My daughters adore her. Jo's passionate about horses and Elaine bought her a horse when she was 13. When Sophie was 13, Elaine took us to Disneyland. She's a bubbly, fun person to be around.

I used to get nervous for Elaine before a show, but not any more. She likes to be really well prepared for a role; she's very hard on herself. I'd never want to put myself through that kind of stress.

Three years ago, around Christmas, when she was starring in The King and I in London, Mum was diagnosed with cancer. Elaine thought she should come out of the show, but Mum wanted her to finish her contract. That was very hard for Elaine, having to go on stage night after night knowing she wanted to be with Mum.

When she left the show, we moved in with Mum and Dad at their home near Bognor. We hadn't lived under the same roof for over 30 years and it was a testing time, but we automatically slotted into the roles which suited us best. I organised the house; Elaine was better than me at hands-on nursing care.

That surprised me, as I'm the one who's brought up a family. Over the five weeks before Mum died, our relationship was strengthened even more.

At home I play all Elaine's videos and CDs. The song Memory, from Cats, still sends a shiver down my spine. I've seen virtually every show Elaine's been in. At the first night of Evita, we were all there. Mum and Dad were so proud. I couldn't believe it was Elaine. My arms ached from clapping. It's the most peculiar feeling, seeing someone who's close to you up on stage. Part of you is detached, but another part keeps looking at this person, recognising mannerisms and inflections in a familiar voice. At Eva Peron's death scene, I was incredibly emotional. But I couldn't work out if that was because of Elaine's acting ability, or because I was watching my sister.