Marti Webb in Tell Me On a Sunday at the St James
Marti Webb in Tell Me On a Sunday at the St James

What prompted you to revisit Tell Me on a Sunday?

I was asked! It all stemmed from the show I did for Don Black, Diamonds are Forever, at the Festival Hall. Lewis Carnie was there from Radio 2 and he asked me, "Could you do it again?" I replied, "well, I suppose so." Robert Mackintosh [producer] from the St James Theatre was also there and said, "Well I happen to have a week free." It was originally going to be a one off to be recorded for Radio 2 and then it evolved into a week. It's taken on a life of its own now, and I can't believe this has all happened from just one appearance. Weird.

I suppose in a sense that mirrors the serendipitous creation of the show

It does a bit, because it just sort of fell into place. As I said to Don the other night, it was only ever made for the three of us. We'd sit there and work on the songs together, and it was so easy in some ways because there wasn't a lot of pressure then. Andrew wrote the songs, Don wrote the lyrics and then we'd record it. Before long we had an album. Then Andrew had the marvellous idea of putting it on television and suddenly I was doing it on the BBC. As luck would have it the football was on the other channel, and at half time everyone turned over to us and got hooked. The BBC was inundated with phone calls from people saying, "we didn't see the beginning," "what happened," etcetera. So it was repeated within three weeks and that's how the album got to number one [in 1980]. My whole life changed overnight.

That wouldn't have happened in a world of iPlayer

No, it's quite nice that we didn't have all that. That was the nicest thing doing this version, the same as the original, that we didn't have to have a computer. I write letters home to my mum from New York and in general I'm much more naïve that women are today. Life was simple then.

So it's closer to the original spirit of the show?

Exactly. Though there wasn't ever really an original production. The only other time I did it was at Andrew's festival at Sydmonton and then when we launched the album at the Royal Variety Performance. It rather went quiet for two years until it came back as the first half of Song and Dance. It had many reincarnations, and each time we did it Don changed the lyrics and updated them. We decided to go back because we wanted to do the original album, unlike the television one. We added "The Last Man in My Life" because Andrew loves that song. We also put in a very short reprise at the end of "Take That Look Off Your Face", because he liked the idea that it started and ended with that. There were a couple of lyrics that Don edited, but otherwise it is basically the original album.

Are you approaching the character any differently because you're at a different stage in your life?

Oh no, I can't play her any differently than I've always played her. There's a little joke that we do where I have a slight pause after the line, "we can have some kids as well", which the audience loves. I mean we need to get that out of the way because, obviously, I'm not pretending to be young anymore! I'm not pretending to be anything really, I'm just me. We didn't alter it that much because once you start doing that it becomes something altogether different. And anyway, it's not like we're doing a big stage production. There's hardly any set, it's just me and the band, which is lovely.

And the extended West End transfer is testament to its enduring appeal

It's lovely that the public wanted to see it because that's what you do it for. The songs are so beautiful and it's everybody's story, that's the thing. There are many people I've met over the years who've said "Oh, it's the story of my life." I think that's the appeal of it. She's an ordinary girl, not some starry person, who goes through these affairs. Everybody's been through one or another, somewhere along the way.

Does she have a name?

No. She doesn't have a name; she's never had a name. I have a name for her and when it went to America Don and Andrew had a name for her. But she's always been the unknown girl. She's always just been 'the girl'. She was given the name Emma on Broadway, but that was a very different version.

How does it feel to be singing those songs again?

It's been a long time since I first sang those songs, but I was surprised to find they're all still in my memory. They are such fabulous songs and they are all in my keys; they are my songs really. It was lovely finding it again, just finding it in my voice.

How do you assess the way Andrew's work has evolved over the years?

What can I say, I'm a bit biased. But I love singing his music, I've loved it from the first time I sang in Evita. It's just so beautiful. He writes emotion, and as a singer that's wonderful. The words are there to tell the story but the emotion is in the music. To be so heavily associated with a musical written by Andrew Lloyd Webber and Don Black, it's the pinnacle. I'm a very lucky girl.

Tell Me on a Sunday transfers to the West End's Duchess Theatre from 18 February 2014 for a three-week run