One lunchtime in August 1948, Peter Finch was doing Molière on the shop floor at O'Brien's glass factory in Sydney when Laurence Olivier and Vivien Leigh turned up.

Olivier and Leigh were the king and queen of the British theatre. He had been knighted for conspicuous enunciation in tights and she had won an Academy Award for her Scarlett O'Hara. Married since 1940, the golden couple were touring Australia to stiffen the post-war cultural sinews of the Commonwealth and raise money for the cash-strapped Old Vic theatre company.

With his expressive cheekbones, resonant voice and luxuriant wavy hair, Finch was Australia's most promising actor. A veteran of outback tent shows, a Dad and Dave film, army service in the Middle East and a role in Rats of Tobruk, he wowed the factory workers and sandwich-munching secretaries. Vivien and Larry thought him marvellous. If ever he was in England, he should get in touch.

Three months later, Finch arrived in London and Olivier put him on contract. By then, all was not well with the royal marriage. On their return from Australia, Vivien announced that she now loved her husband "sort of, well, like a brother."

Soon after, while playing Blanche duBois, her manic-depression became a full-blown pathology. She slept with everyone and anyone, suffered delusions and started to go completely starkers. By the time she won an Oscar for Streetcar, she was beyond even Hollywood's pale. To get her out of sight, she was offered the lead in Elephant Walk, to be shot in Ceylon. The male lead would be Peter Finch.

There had been earlier rumours of an affair but things came to a head during the filming. Both were drinking heavily and they spent the nights together on a hillside under the stars. The script called for Leigh to escape a giant anaconda and a herd of stampeding elephants. It was too, too much. She slipped into paranoia, began to hallucinate and trailed after Finch, calling him Larry.

Olivier was summoned, "anxious to see the state of the union". He abdicated his wife to his protégé and returned home, "in a soft coat of numbness".

The shoot was cancelled and Leigh replaced with Elizabeth Taylor. The lovers ran off to the south of France, held hands at Stratford and drove poor Larry to his wit's end. Vivien was, after all, Lady Olivier.

It was all too fraught for Peter, too. He went on to A Town Called Alice and, ultimately, his own Oscar, posthumously, in 1977, a category first. By then, the curtain had long fallen on the fragile beauty that had been Vivien Leigh.