Joan Collins described sister Jackie as the “rock who kept the family together, but a new documentary reveals the best-selling author was plagued by self-doubt and personal pain.

And behind the successful and ­confident public image she wore like a shield until her death in 2015– along with her “Girls can do anything” mantra – she spent her life struggling to live in her elder sibling’s shadow.

Lady Boss: The Jackie Collins Story has interviews with Jackie’s closest friends and family, including Joan – and even gained access to the diaries she wrote as a teenager.

Jackie’s friend Tita Cahn, daughter of songwriter and musician Sammy Cahn, says: “I think she suffered from the baby sister syndrome. Joan was extremely beautiful. I mean a natural beauty with flawless skin.”

Joan Collins was three years older than her sister Jackie (
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WireImage)

Jackie was born in 1937. Her ­domineering father Joseph was a ­theatrical agent whose clients later included Dame Shirley Bassey and Sir Tom Jones.

Joan was born three years before her, and made her stage debut at the age of nine. By 16 she was RADA trained and well on her way to stardom.

Jackie tried to catch up but things did not go her way as easily.

Her acting career got off to a bumpy start and she lacked Joan’s confidence.

One thing she always did well though was write and make notes about everything.

She made up racy stories for her school friends, much to their delight.

It was a trick she would repeat on a grander scale years later. In her diary on May 14, 1953, at the age of 15, Jackie wrote: “Went to a party with Joan. It was fun. I get awful ­inferiority complex when I’m with Joan. I feel all big, clumsy and dull.”

Jackie's acting career got off to a bumpy start because she didn't have as much confidence as her sister (
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Mirrorpix)
Jackie Collins was presented her Officer of the Order of the British Empire (OBE) medal by Queen Elizabeth II (
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Getty Images)

On October 28 she added: “Daddy said I looked like a tart. Makes me sick.”

Jackie’s daughter Tracy says: “Mum would have looked at her sister and thought, ‘Wow, look at the attention that she can get just from being beautiful.’

Meanwhile mum was told all sorts of things by her father – she was not beautiful enough, not slim enough. I don’t think that ever left her. Girls can do anything, that was her motto.

Jackie is said to have face self-doubt throughout her life - even when she was a successful author (
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Mirrorpix)
Joan Collins said she 'cried every day for three months' after the death of her sister Jackie to breast cancer (
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Getty Images)

“As much as she was saying that to ­everybody else, she was consistently saying it to herself.”

At 15, Jackie got expelled from Francis Holland School in London for truancy and smoking. She had already got a taste for going out to nightclubs with her sister.

Jackie did get acting work in British B-pictures and TV. Joan adds: “She played opposite Roger Moore in The Saint. Then Daddy sent her off on the variety circuit and was billed as Joan Collin’s younger sister which I think infuriated her.”

Jackie Collins pictured with her older sister Joan Collins in Los Angeles in 1983 (
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Ron Galella Collection via Getty Images)
Joan Collins aged 6 with her little sister Jackie Collins aged 2 (
Image:
Alpha Press)

Jackie, awarded an OBE in 2013, was persuaded to write by second husband and love of her life, ­American Oscar Lerman. After reading some of her notes, this time for The World Is Full Of Married Men, he told her: “Finish this one, you’re a storyteller.”

The release of the book in 1968 was met with an outcry over the sexual content. Romantic novelist Barbara Cartland called the book “nasty, filthy and disgusting” and accused Jackie of “creating every pervert in Britain”.

But many women credited Jackie with teaching them everything they knew in the bedroom. Jackie’s books sold more than 500 million copies.

Jackie Collins was the 'rock that kept the family together' (
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Mirrorpix)
Jackie Collins eventually turned her hand to writing after being persuaded by her husband Oscar Lerman (
Image:
Getty Images)

The film also follows her final days in 2015, including a ­return to London for a farewell to Joan and brother Bill. She had been diagnosed with breast cancer six and a half years ­earlier but had only confided in her three daughters.

Recalling their last lunch together at the Ritz before she died, Joan says: “She said, ‘Now I have to tell you something. I have stage four breast cancer.’ I said, ‘It is not possible.’ There were no goodbyes. It was like, ‘I will see you all at Christmas.’

“I was in the south of France and my cell phone beeped and I turned it on and they said, ‘She has passed.’ I cried every day for three months. I miss her.

“She had an incredible life. It was shattering when she died as she was the rock that kept our family together.”

  • Lady Boss: The Jackie Collins Story was shown last night at the Tribeca film festival and is available to buy on demand in the US from today. It will air on CNN on June 27 and on the BBC later this year.

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