Keeley Hawes reveals what to expect from the newest series of The Durrells

The quartet of precocious but under-disciplined Durrell youngsters are constantly getting into scrapes, ignoring their mother’s advice or, in the case of young Gerry (Milo Parker), filling up the ramshackle family home with exotic pets.

Most mums would long for the day when such offspring would fly the nest and give her some peace.

And yet in the third series of The Durrells, which starts this week, Louisa finds it difficult to cope with the idea of her little ones pulling away from her.

And mum-of-three Keeley feels exactly the same. “There’s a line in the script about how every year the children all move further away from Louisa,” recalls Keeley, 42.

“It talks about, ‘The last time I brush your teeth for you, the last time you let me hold your hand as we cross the road.’ It’s heartbreaking! And it’s so true. I do remember the last time I brushed my children’s teeth for them.

“Our writer, Simon Nye, is so good at that because he’s got children, been there and done it. He deals with all of that so beautifully.”

Keeley knows all about it, too, as mum to Myles, 17 (from her first marriage), and Maggie, 13, and Ralph, 11, with her husband, actor Matthew Macfadyen.

Watching her youngest leave childhood innocence behind is particularly painful for Louisa. Keeley says the most moving scenes of the series – set in Corfu in the 30s and based on Gerald Durrell’s books – were those involving young animal-collector Gerry, played by Milo Parker.

“It’s been really exciting for Milo,” says Keeley.

“He’s had some lovely scenes where Gerry is changing and growing up. I think it’s addressed in a brilliant way, and anyone with an angry adolescent will be very sympathetic! It’s a learning curve for all of us.

“There’s one scene with Gerry involving a poem he’s written about his mother. And I can’t even read the scene without crying my eyes out. It always has this added layer, when you know these were real people. It’s heart-wrenching, but they are some of my favourite scenes. Louisa knows Gerry will grow up and has to accept it – eventually, Louisa’s children did fly the nest.”

But not quite yet. As we revisit the Durrells in sun-soaked Corfu, Louisa’s brood is still around to infuriate her – and for her to meddle with. After several disastrous romances of her own – Louisa nearly married a gay man, and her last lover tried to wrench her away from Corfu – she decides instead to get involved in son Leslie’s (Callum Woodhouse) love life after discovering that he has three girlfriends on the go.

A disapproving Louisa sticks her nose in, much to Leslie’s mortification.

But Callum Woodhouse explains that Leslie’s boorish behaviour is more forgivable than Louisa finds it.

“It’s obviously a very bad thing he’s doing, and I thought that as I was reading it,” says Callum.

“But when I got to why he does it and his insecurities about himself, I empathised with him. It’s good to explore a vulnerable side to Leslie we haven’t seen before.”

As for Louisa’s other children, Larry (Josh O’Connor) is writing his third novel, but Margo (Daisy Waterstone) is restless, looking for something to occupy herself.

“Margo gets into soap sculpting as a way to pass the time, and generally everyone thinks she’s mad,” explains Daisy with a laugh.

“Eventually, Margo discovers that Theo [Yorgos Karamihos] has started this X-ray unit at the doctor’s surgery and she volunteers to work there. She’s quite good at it.”

And as the series progresses, viewers will wonder if Louisa’s love life is as dead as all that.

Although a relationship with married friend-of-the-family Spiro (Alexis Georgoulis) is out of the question, the pair are clearly attracted to each other.

“We go a bit deeper into their relationship in this series, which is very exciting and easy to play, because Alexis is brilliant,” says Keeley.

“We get on so well and really enjoy those scenes.” But she admits that their on-screen relationship has a bittersweet flavour.

“Louisa and Spiro would be so good together. They’re both wonderful people, but Louisa would never go there because he’s married, with a couple of children. It’s 1937 and a very different time. But wait and see what happens.”

Matters come to a head when Spiro puts Louisa’s nose out of joint – he welcomes a new family, of Italians, to the island just as warmly as he welcomed the Durrells.

“Louisa questions whether Spiro is really her best friend, or if he’s just being polite, as he is to the new family,” explains Keeley.

“It really throws her. She becomes very jealous and competitive with them.”

Ultimately, however, things will work out for the best. That’s the optimistic message of The Durrells, whose sun-drenched Greek vistas can’t help but warm up the coldest of Sunday evenings.

Even with Louisa’s various heartaches, The Durrells is comforting telly.

“It’s like the Victoria sponge of TV, in the loveliest way,” quips Keeley.

“Because it is comforting, and you can forget about all those other things just for a little while.”