'Ooh Betty, you are doing well'

Michele Dotrice, best remembered as Betty in the 1970s comedy sitcom Some Mothers Do 'Ave 'Em, was gobsmacked when I told her I'd read that the programme's stock phrase, 'Ooh Betty!', was uttered only once (Series 2, Episode 2) by co-star Michael Crawford (on-screen husband Frank Spencer) in the show's entire history.

'I didn't know that. How amazing! I shall tell Michael. People used to say it to me all the time – and I would say yes, like I'd never heard it before. Back then, in the 1970s, every impersonator was doing a Frank Spencer. So much so, it was quite intolerable for Michael to go out. He virtually became a recluse.'

Some Mothers Do 'Ave 'Em started as a simple half-hour comedy show in 1973. When its final show aired on Christmas Day in 1978, it had amassed an audience of nearly 26 million, Michele tells me. 'It's extraordinary what e‚ ect a half-hour show can have when it's a success. It catapulted me into di‚ erent areas, which was tremendous.'

Dotrice started acting at the age of 11 with a walkon part in The Gentleman Of Verona. 'There was a young boy in the company, walking on too,' she says. 'He was called Dennis Waterman – he didn't do too badly for himself.'

She joined the RSC at 16 and went on to star alongside such actors as Ian Holm in Henry V. 'I worked with the finest directors and also not a bad writer, that Mr Shakespeare!' But at 24, Michele was o‚ffered the part of Betty Spencer and left the company to take up the role as the long-su‚ffering wife of Frank.

'They were very happy years working with Michael. In fact, we went to see Spamalot recently, that is, Michael, his partner, the director of Spamalot and me. During the second act, Marcus Brigstocke (who was doing the first few shows) started to do a Frank Spencer on stage – apparently every night they do di‚fferent things, and somebody had said we were out front. The audience was in hysterics, I was in hysterics... Michael was dying – sinking down in his seat and I was going down with him.

'He's 70 and I'm 64, but the audience reaction was tremendous.'

There is something so fitting that, having played Britain's best-loved comedy couple, Crawford and Dotrice should remain friends almost 40 years on. 'We hadn't been in touch for many years, but when I was doing When We Are Married (2011), Michael got in touch. He's been very supportive of me, and most kind. He came to see me recently and asked how I was getting on with The Ladykillers. I said, "Well, it's OK – I have a lot to learn."

'Right there and then, he started to do Mrs Wilberforce in front of me. I said, "That's it, Michael. You'll have to play the part." He'd be marvellous as Mrs Wilberforce – it did unnerve me bit.'

Dotrice is currently rehearsing Mrs Wilberforce for Graham Linehan's stage adaptation of the 1955 film, The Ladykillers. Set to tour Britain and Ireland, the season has just opened at the Theatre Royal, Plymouth. 'It's beautifully constructed, with marvellous characters. A real ensemble piece. Mrs Wilberforce is a super part to play – a darned good yarn.'

Also starring Clive Mantle, Paul Brown and Shaun Williamson, the show promises to deliver and should delight audiences, not least for the improvisational twist it is set to include. A number of tour venues have agreed to take part in the Nominate Your Nan scheme, an initiative designed to encourage local women of 55 and above to get involved in the show when it arrives in their vicinity. Four non-speaking roles are up for grabs, and producers are hoping family members will nominate their grandmothers to take part. While the roles last just five minutes and require no acting experience, having 'amateurs' in the cast will no doubt up the comical ante.

It wasn't comedy that first attracted Dotrice to the show, but her late husband, actor Edward Woodward, was a fan of the film. 'It was one of his favourites. I think my boy's up there helping, I really do,' she says. She talks a lot about Woodward, and it is evident that theirs was a loving union. Woodward and Dotrice wed in 1987 (his second marriage) and remained together until his death in 2009.

'When Edward was in America doing The Equalizer, and during the years we were in New York with our daughter [actress Emily, 29] I took a back step,' says Michele. 'There was no way I was going to leave him to do a show.'

After losing her husband, Dotrice broke away from acting. 'It was When We Are Married that brought me back, which was the right thing at the right time because it just so happened to be Edward's favourite play – like a gift that was sent to me,' she says touchingly. 'Now I'm back in again and it's wonderful – exciting, frightening and very therapeutic.'

Though clearly scarred by her loss, Dotrice seems content with where she is today. 'I'm blessed,' she says. 'Since I've lost Edward, I've had two beautiful roles.' She still has one ambition, though – to star alongside her daughter. 'To do something with Emily would be such a joy. It might not be for her, having her mum on stage...'

I doubt Emily would mind – for who could argue against performing on stage with an amusing, talented actress, who just happens to be your mother? After all, some children do 'ave 'em, don't they?

The Ladykillers is currently on a 26-week tour of the UK and Ireland. For venues, visit www.theladykillers.co.uk – for further details of the Nominate Your Nan scheme, see the website for venues.