It was a touching sense of vulnerability that drew us to both Dianas. "Dors's life was an open book for everyone to take a page out of," Redman continues. "She spilt her guts and lived her life in public. She was the first Hello! person. You had to empathise with her. The Princess of Wales was the same. Maybe that's the key to getting people to love you."
It may be sentimental, but people are obviously also moved by stars whose lives are tinged with sadness. After once being touted as Britain's answer to Marilyn Monroe, and shining as a woman on Death Row in the 1955 film Yield to the Night, Dors's weight ballooned and she ended up with crippling debts. Having endured many setbacks in her personal life, she eked out a living on such game shows as Celebrity Squares, before dying of cancer in 1984, aged 52.
"There's always a sense of tragedy with icons," says Keeley Hawes, the actress who plays the young Dors in The Blonde Bombshell. "It happened to both the Princess of Wales and Diana Dors. A lot of people had grown up with them, and everybody loved them. Then, when they had at last found happiness, they were taken in the most dreadful way. That's heartbreaking, especially as they had already suffered so many tragedies in their lives. People respond to that. We felt like we knew these people and could talk to them."
Part of our affection towards Dors stemmed from her indomitable sense of chutzpah. "Dors once pulled up in a sparkling Rolls-Royce," Hawes recalls. "Wearing the full works, she leaned out of the window and shouted to a friend, `Can I borrow 50 quid to pay for the lunch I've just had?' She was more than capable of laughing at herself - which is a lovely quality. She was a star, but there was nothing starry about her. She was approachable - and that's a real talent. People didn't see Marilyn Monroe as approachable - she was always `Marilyn, the movie star'. But Dors was always `Diana, the people's friend'."
Redman also underlines Dors's extravagant personality. "Largeness is the only word you can use. She was large in every way - large house, large car, large hair, large body."
The public also warmed to the survivor's instinct in Dors; we Brits love a bit of true grit. "She was a woman doing things on her own," Redman remembers. "She was terribly in debt, and the Archbishop of Canterbury said she was an unfit mother - that must have been hard. But, as she did all the way through, she just stuck up two fingers. She was a rebel. If there was some sort of problem to overcome, she'd think, `Good, that's better than plain sailing'. Life for her would have been boring without challenges. You can't help but admire her balls.
"People could learn from her how to survive against the odds. She was of that generation that would never show the neighbours how broke they were. There's a lot to be said for that - put on a front and you become it. She encapsulated the Blitz spirit. She was very British. When the chips are down, we all say `brilliant' and start singing."
`The Blonde Bombshell' is on ITV on Mon & Tue at 9pm