As matriarch of an acting dynasty Joanna David has successfully played the role of mother and wife as well as maintaining a glittering career that spans both stage and screen, but her favourite backdrop will always be Dorset

Joanna David could only be an actress. As the Downton Abbey star – and real-life matriarch of the stagey Fox dynasty - says, with trademark self-effacing charm: “I hate being myself.”

She is married to Day of the Jackal’s Edward, the brother of Charlie and the Chocolate Factory’s James. Their children, Emilia (Millie) and Freddie, are in the business: Silent Witness, The Shadow Line. So too, Joanna’s nephew Laurence. They all clearly share a genetic compulsion to act.

“We’ve got nothing to be starry about, not at all,” she says, sweetly. “Acting is just what we know. Millie initially thought about journalism but she then did so much drama at Oxford, that’s what forged her.

“Freddie knew he wanted to be on stage from the word go. We didn’t discourage them but we certainly never said: ‘make the theatre your career’.

“Both went into it with open eyes. They haven’t been shielded from the times we’ve been out of work: they saw the glamour but they also saw the grit. Edward and I are just lucky to be able to carry on into old age.”

Twinkly still at 67, Joanna looks a good ten years younger – annoyingly, actors always do - in her white jeans and silver bangles, despite her patently untrue claim: “I look ancient, about 106.”

We meet at her local restaurant, Clavell’s (“the best beef I’ve ever eaten”) in Kimmeridge, Joanna’s home for 33 years.

“I used to rent a house in the village, overlooking the bay, before I met Edward in 1971 – we were in a play together. And we carried on renting for another 12 years until we were lucky enough to buy our house. Edward was told that – in his 40s - he really should get a mortgage. It’s wonderful, tucked away.”

Joanna is driven – having just finished a month-long run of Hobson’s Choice in Regent’s Park – but she is equally selfless, in that endearing luvvie way.

She insists on paying for coffee, she frets about our photographer in the heat and she calls everyone “darling”.

When Edward shot to film stardom, Joanna put her career on hold. “Ed didn’t insist on it,” she says, without rancour, “but someone had to be at the helm of the home and he was earning more than I was.”

She was mindful of her own childhood, derailed when her father, a businessman, went bankrupt and walked out, never to return, when she was just ten, leaving her mother to bring up three children on her own.

But the family upheaval was the making of her.

“I never saw my father again. But I got a scholarship to ballet school at the age of 12. If he hadn’t left us homeless in Stepney that might not have happened.”

Four years later, she became a chorus girl, the youngest of the Laguna Lovelies in Clacton-on-Sea’s end-of-the-pier show with Roy Hudd.

“It was the best thing that ever happened to me. I was in front of an audience and I adored it.”

From there, drama school could only beckon. But for Joanna – who took the stage name of David in tribute to her mother after she died of bowel cancer – family is all.

She admits: “I’ve stood back but I’ve kept going which is all I care about. I used to take Millie on tour with me in the school holidays.”

Joanna eventually made her name with the BBC in 1979 as the heroine of Daphne du Maurier’s Rebecca, a role later also played by Emilia. And from Agatha Christie to Inspector Morse to Downton Abbey, she has seldom been out of work for long.

“I would hate it if I didn’t have work as a stimulus in my life. I would be very lost.”

She has needed that bedrock. Hard though it is to imagine now, Joanna has suffered from two bouts of serious depression, once after a brain operation 22 years ago (to cure a neurological condition which had damaged her spinal cord) that put her in a psychiatric hospital for a month.

Then, she was laid low again in 2010, this time by a seizure caused by Ménière’s disease, which affects the inner ear and balance.

She says: “I seem to be over the Ménière’s thanks to medication that I still take, but it took a bit of time. Wonderful doctors and my family got me through but it did leave me in a terrible state.

“But it’s good to be able to say to anybody else in that situation that there is light at the end of the tunnel. It’s important that people should know you can get well from depression.”

Joanna is devoted to Rose, Emilia’s three-year-old daughter (from her relationship with film-maker Jeremy Gilley) and fiercely protective of them both.

Emilia’s private life has come under particular scrutiny. An engagement to Vic Reeves was followed by a three-year marriage to Richard Harris’ son Jared and, then, the short-lived relationship with Gilley, which ended soon after Rose’s birth.

“Who wants your life talked about? Millie loathes that side. People always say to me ‘Gosh, your daughter must have such an amazing life on television.’ But Millie goes to work at six in the morning and comes back at eight at night. She loves her job but she adores her daughter. Rose doesn’t understand that her mummy is on telly, she couldn’t care less. Thank goodness, they have a wonderful nanny. And I adore being a granny. We’re still in charge at Christmas and Easter. That’s wonderful.”

Emilia, 39, and Freddie, 25, both went to boarding school in Dorset – Bryanston in Blandford - and love the county. Freddie learned to fish in Kimmeridge and when she was a 15-year-old, Millie was a waitress in the village.

Joanna is impossible to dislike. Smiley and kind but theatrical, she seems to be chums with everyone: from the Duchess of Cornwall to Julian Fellowes.

Her appearance last year on Fellowes’ Downton Abbey as the Duchess of Yeovil was almost a school reunion.

“Julian and I go back a long way. We were in Colditz together in the Sixties and then Monarch of the Glen. He’s a dear man. His mother-in-law Ursula Kitchener is an absolute delight, quite wonderful. I was very sad not to be able to go to her 90th birthday this summer.

“I’ve known Maggie Smith ever since her two sons were tiny. She was a close friend of my amazing mother-in-law, which is how I first met her.”

Joanna and Edward have just celebrated their 10th wedding anniversary. They married in 2004 after 33 years of living together.

“Edward never asked me to marry him,” she says, “but we eventually did it because the accountant - or maybe it was the solicitor - said: ‘You really ought to sort your life out and get married before you kick the bucket’.”

They are nothing if not troupers. Next, Joanna is recording a Radio 4 production of War and Peace. Edward, still dapper at 77, is off to star in An Ideal Husband, opposite Patricia Routledge, at Chichester.

“As long as we can still learn our lines,” says Joanna, with one last giggle, “we’ll stumble on.”

You’ve got to love an old pro.

Joanna David’s Dorset

Favourite restaurant: Clavell’s in Kimmeridge. Emma and her family have turned this place around in just four years. The food is incredible - I cannot describe how good it is. You see all these horribly expensive restaurants in London and then you come here and have wonderful home cooking in an amazing location for a very reasonable price.

Favourite shop: Mr Curtis the butcher in Wareham is fantastic. The health shop is fabulous too.

Favourite walk: Tyneham is on our doorstep and that walk to the beach is dazzling. We used to take Millie and Freddie as children, now we take our granddaughter Rose.

Favourite discovery: Dorset is so beautiful, varied and unspoilt. I’m ashamed to say I only recently discovered Arne, the bird sanctuary. I’ve been twice and had such a fascinating time, looking out to Brownsea Island. I’m not very knowledgeable but I am very interested.

Favourite pub: We’ve got a great friend who’s a brain surgeon – he operated on me 22 years ago. His wife’s a GP and they love walking. So we all went to the Square and Compass recently and then walked towards St Aldhelm’s Head. Magnificent.