A cache of unseen letters written by Hollywood star Audrey Hepburn has revealed her highs and lows as she rose to movie stardom.

And they include the poignant letter she wrote to a friend about her break-up from Huddersfield tycoon James Hanson.

The pair were engaged for almost a year but broke up as their work schedules kept them apart.

Hanson, who was knighted in 1976 and created Baron Hanson of Edgerton in 1983, went on to build up a huge industrial empire with his business partner Lord White.

The pair formed a partnership in the 1960s, and founded a greetings card business. They began buying other companies, in such diverse industries as fertilisers and bricks, which all sat under the umbrella of a listed entity called Hanson Trust, later renamed Hanson.

Star of "Breakfast at Tiffany's" , Audrey Hepburn, with James Hanson at the time of their engagement.
Star of "Breakfast at Tiffany's" , Audrey Hepburn, with James Hanson at the time of their engagement.

By the 1980s, they operated in both Europe and North America, purchasing undermanaged businesses in sectors such as batteries, locks and safes.

Hanson dated actresses Jean Simmons and Joan Collins before meeting Hepburn, and the pair became a regular couple in the newspapers.

Now Hepburn’s letters are up for auction. The 10 intimate notes were sent between 1951 and 1960 to actor Sir Felix Aylmer – her mentor in her early career and a lifelong pal.

She spells out her ­feelings on her broken engagement, her new love and the birth of her first child.

The letters from Audrey Hepburn up for auction

In 1951, aged 22, the budding star wrote: “Would you believe it. I’m in Monte Carlo working on a French picture. The place is heavenly and this is the best thing that’s ever happened to me.”

The upbeat actress, once a struggling ballerina, was filming for Monte Carlo Baby, one of her first films.

But a year later, she tells “with a heavy heart” of her split from fiance James Hanson, which came after he pushed her to tie the knot amid her hectic shooting schedule.

Hepburn had been in Rome wrapping up her breakthrough film Roman Holiday while Hanson was snapped leaving London nightclubs with other actresses and socialites.

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“It is all very unhappy-making,” she wrote from Chicago months later. “I fear I thought it possible to make our combined lives and careers work.”

By 1954, she had met accomplished actor Mel Ferrer, who was 12 years her senior, and found true love.

The letters, which remained within the extended family of Sir Felix, will go under the hammer at Bonhams Entertainment ­Memorabilia in Knightsbridge, London, on June 29 and have an ­estimate of £3,000 to £4,000.

Lord Hanson died, aged 82, on November 1, 2004 after a long battle with cancer, at his home near Newbury, Berkshire.