Her latest role sees her playing a bad-tempered old woman who has a fractious relationship with her daughter, but thankfully Dame Sheila Hancock gets on far better with her own three grown-up girls.
That doesn’t, however, mean she’ll be leaving them everything in her will.
Sheila, 88, who was married to Inspector Morse actor John Thaw until his death in 2002, plans to leave a considerable chunk of her fortune to a charity she set up in his name.
“A huge amount,” she emphasises. “The bulk of what I leave will probably go to charity.
“I set up the John Thaw Foundation in John’s memory after he died. It gives money to small things that are going to make a difference.
“I want them to have a big lump sum for the work to continue after I’ve died.”
Actress Sheila, who is mum to Melanie, 56, Abigail, 55, and Joanna, 47, says her daughters are all “happy” with her decision.
“I don’t care if they’re not!” she laughs. “My children have had loads during their lifetime. They’ll be all right.”
Sheila isn’t planning to go anywhere anytime soon, however. Since making her name in 1960s sitcom The Rag Trade, she has performed on Broadway and in the West End.
Her TV career has included parts in series as varied as New Tricks and EastEnders to Sky’s A discovery of Witches.
And in her latest role in ITV police drama Unforgotten, she plays irascible mother Eileen. It is one
she has tackled with relish.
She stars as the mother of Liz, played by Susan Lynch – one of four newly-qualified police officers whose car was pulled over near a murder scene in 1990.
Police are now reinvestigating the cold-case killing after the body of a dismembered man was found. Sheila says: “My character says she wishes she was dead because she has no life. Generally, she sees no reason to get up.
“They had her in pyjamas and I said she should be in a terrible old jumper, as though she’s just thrown something on and gone back to bed. She’s not bed-ridden, but says, ‘What the hell do I get up for?’
“She really has nothing in common with her daughter.
“She loved going to concerts and her friends were intellectuals and her daughter is in the police. They really don’t like one another.
“We did some improvisation on a scene where she washes my hair and they thought we were genuinely having a row.
“I was saying, ‘You’ve got the bloody shampoo in my eye!’ They said, ‘Cut!’ and all looked very embarrassed and we said, ‘We’re acting!’”
Like many others, Sheila has been struggling to cope with life in lockdown. “You have to be very careful about your mental health,” she says.
“Whereas I was busy, busy, busy before all this happened, now I spend hours not saying a word to anyone.
“I know that my brain is not functioning as sharply as it did. Hopefully it will again but at the moment, I am slower on the uptake than I normally am. Also, I’ve got rheumatoid arthritis, which is no joke.
“I normally go to the gym every other day and that’s how I’ve kept it under control but there’s no gym at the moment and I don’t have the discipline to do the exercises at home.”
Sheila is busy making plans for when lockdown ends.
She was recently made a dame in the New Year’s Honours list for her services to drama and charity and is desperate to do more to help people.
She says: “Now I’ve been given this dameship, they’re going to bitterly regret it! I’m going to use it to try and open as many doors as I can, certainly in the world of education. I feel strongly that I’ve got to earn it.”
Sheila, who is a firm believer in education, is patron of DigiSmart – an IT learning system for children aged nine to 11 who are falling behind with their reading and writing.
She says: “I’m desperate for all children to have iPads, and even then there are children who need a teacher in the flesh, encouraging them.
“I’m involved a lot in education and I know the schools are having the most dreadful time. The teachers are struggling. A lot of what they’re being asked to do is so unrealistic.
“It couldn’t be harder than it is for the youngsters now. Both for children and certainly my grandchildren, who are university age, it’s wretched.
“It’s a time when they should be having fun, learning and enjoying themselves but they’re stuck in their rooms and it’s all being done online. It’s awful.”
Sheila’s three daughters all became actresses and she now has eight grandchildren, ranging in age from nine to 25. “They’re all activists of one sort,” she smiles proudly. “They’re apolitical, which is so different from when I was young.
“They support causes – Black Lives Matter, equality, #MeToo. They’re all on the right course and they’re really working hard to change things.”
As passionate as they are, it’s hard to imagine any of them can match their inspirational grandmother.
She says: “I know there comes a time when you think, ‘Oh hello, I’ve had enough of this, I’m off’. I’m sure that will happen to me, but until that happens there’s so much to be done.”
*Unforgotten, ITV, Tuesday, 9pm