A bottle of Prosecco in Dame Diana’s trailer. That clause was written into Diana Rigg’s contract when she played the Duchess of Buccleuch in ITV’s Victoria at the age of 79.

Still oozing charisma and bursting with acting vigour, she had no intention of giving up her lifelong habit of a glass of fizz before going on set or onstage.

As her only daughter, the actress Rachael Stirling writes in her deliciously readable and deeply touching mother-and-daughter memoir, ‘I would love to have a nightly glass of champagne before going on stage, but these days it would equate to a drinking problem.’ Instead, Rachael has settled for eating ‘a grain or two of my mother’s ashes’ on the first night of a new play.

When Toby Jones was on location with Rigg in Shanghai in 2005, he tried to match her drink for drink one evening. The next morning, he was horribly hungover – ‘the worst he’d ever felt after a night out’ – whereas Rigg was ‘waggly-tailed’.

The fizz in her Prosecco echoes the fizz of Rigg’s whole approach to life. ‘Diana has been tiresome in the dormitory,’ wrote the matron at her dreary post-war boarding school, St Christopher’s in Great Missenden in the Chilterns.

She was ‘slapped down mightily’ by her austere Doncaster grandparents when, aged seven, she painted her lips with beetroot juice to see what she’d look like in lipstick.

When she set out as an actress at the Royal Shakespeare Company (RSC) under Peter Hall in 1960, her habit of collapsing with giggles on stage posed a threat to her career prospects. Hall’s wife, Leslie Caron, said to her, ‘You have to think of something sad, Diana. Think of being fired.’

That did the trick. Rigg was seriously ambitious. Determined to get ‘bums on seats’ in theatres after a few decent RSC parts, she worked out that she needed to cross over to television to gain fame.

Sixty women applied for the part of Emma Peel in The Avengers, replacing Honor Blackman in 1964. Rigg got the part. She had the requisite ‘M-appeal’ – ‘man-appeal’.

Chemistry crackled between her and Patrick Macnee as Steed, and she had the sense of humour for the part. So those irrepressible high spirits came good.

It was a brilliant career move. Diana Rigg as Emma Peel in her Sixties catsuits became the ultimate sex symbol. In 2002, Rigg and George Clooney were voted ‘the sexiest TV stars of all time’.

An estimated 20 million people watched each Avengers’ episode. Rigg was inundated with fan letters. A typical one went, ‘I have been in love with you ever since you picked that fellow up and knocked him over and smashed him through the glass roof.’ Diana’s reaction was, ‘I seem to appeal to the fourth form and under.’

As ‘the embodiment of female empowerment’ in her Avengers role, it came as a shock to discover she was being paid less than the cameraman. She was not a bra-burning feminist – ‘I need my bra!’ – but she had one simple demand: equal pay.

She didn’t get it. ‘By the mid-Eighties,’ Stirling writes, ‘20 years after The Avengers was originally aired, the show was playing on a loop on American telly and Patrick Macnee was living off the fat of his royalties while Ma would get the occasional cheque for 28 pence.’

Her high spirits were not always good-tempered ones. Stirling catches the tone of her mother’s voice unforgettably. She could be impatient, waspish, jealous. When Judi Dench’s career blossomed in old age, Rigg said, ‘Why are they always casting Mrs F*****g Tiggywinkle?’

On set for her role as the Queen of Thorns in Game Of Thrones aged 74, Rigg texted Rachael, ‘Just done the scene 23 f*****g times. I am not an actor. I am a robot.’

‘Thank you. Go away!’ she snapped at a cameraman who dared to try and give her notes on set.

‘Oh he was ghastly!’ she said of George Lazenby, whom she nicknamed ‘POG (‘Poor Old George’), when she was his Bond girl in On Her Majesty’s Secret Service – and killed off.

Lazenby, an Australian model, had no previous acting experience and was like a spoilt child, turning up late, and sulking. He publicly accused Rigg of sabotaging a love scene by eating garlic on purpose just before arriving on set. She had indeed eaten garlic, but not on purpose.

Rigg’s most memorable furious moment was when, on the day she found out her husband Archie Stirling was having an affair with a younger woman (Rachael doesn’t name the woman, but writes ‘you’ll look it up’, and I did – Joely Richardson, Vanessa Redgrave’s daughter), she rang for five taxis, put all of Archie’s bespoke suits into them, and directed the drivers to dump them at charity shops all over London. He returned home to an empty wardrobe.

S he was not always easy as a mother, either. Though brimming with love for Rachael, she was unencouraging about her acting career, and could be ruthless after watching her on stage.

Rigg played Medea to critical acclaim from 1992 to 1994; then, when Rachael played Medea in a modern version, Rigg called it ‘a catastrophic failure’.

Stirling writes that she had to go to therapy to sort out the relationship. She puts some of her mother’s behaviour down to insecurities from childhood: there’d been fierce competition between her and her own mother Beryl for her father Louis’s affection.

Rigg’s outspoken remarks are ringing in my ears after reading this book. ‘Jewels must be suckable. Like big fat sweeties.’ ‘Sex is a source of infinite joy. I need it as much as I need food.’ ‘On the whole, avoid rash airport purchases.’

When ill and wanting to be on her own, ‘I’m going to my basket.’

She had a doctor called Dr Ploughman, whom she nicknamed ‘Lunch’.

Having at first taken a dislike to Rachael’s husband, the rock singer Guy Garvey, she then seemed to fall in love with him.

One day, when she’d moved in to live with Rachel and Guy in the last year of her life, she said, ‘Rachie, has there ever been a film in which a mother moves in with her daughter and son-in-law and the son-in-law falls in love with the mother because she is much better in bed?’

And ‘clinkie drinkies’. That was Rigg’s name for her daily 4pm tipple: Campari and soda with lots of ice. She carried on enjoying that right up to her death in 2020, from lung cancer after a life of chain-smoking.

At home in Kensington when Rachael was growing up, the sitting room ‘had a permanent head-height nimbostratus of exhales and inhales – we called it the Health Spa’.

‘I see my mother’s life,’ Rachael writes, ‘as a lesson in living life to the full, in following your instincts, in loving with all your might, in laughing always at yourself first, and in being curious, now and for ever.’