Early in his career, his talent for playing stiff-upper-lipped romantic leads won him flattering accolades such as "Boy's Own Brit". He was acclaimed as a new Errol Flynn or David Niven, whose "flawless looks, perfect features, perfect hair, perfect skin" were admired by one breathless female critic in The Sunday Telegraph.
In 1985 he was touted as a possible successor to Sean Connery and Roger Moore in the role of James Bond. The rumour put MacCorkindale – who had often maintained that he would be a superstar by the age of 35 – three years ahead of schedule. But he never did become 007.
Simon Charles Pendered MacCorkindale was born on February 12 1952 at Ely, Cambridgeshire, the son of Scottish parents. His father, a station commander in the RAF, was sent to 17 different postings in as many years, and Simon spent his childhood in perpetual transit, settling only briefly at various bases in Britain, Germany or Belgium.
Educated at Haileybury, where he was head boy and played rugby, he wanted to follow his father into the RAF, but at 13 failed an eyesight test. After considering a career in the Diplomatic Service, he decided to train for the stage at the Theatre of Arts in London.
His ambition was to direct rather than to act, and indeed he did later find success as a writer and director. But acting parts kept coming, despite his initial intention to remain out of the limelight, and in the mid-1970s he made his breakthrough on television as Lucius, the son of the Emperor Augustus, in the highly-regarded series I, Claudius.
In 1977 MacCorkindale won the role that propelled him on to the international stage, starring as the smooth murderer, Simon Doyle, opposite Peter Ustinov's Poirot in the feature film of Agatha Christie's Death on the Nile.
After co-starring with Michael York and Jenny Agutter in a film version of Erskine Childers's The Riddle of the Sands (1979) and appearing as a younger-than-usual Macbeth at the Ludlow Festival of 1980, he spent several years in California.
But roles in major Hollywood films were not forthcoming. Instead he starred in a short-lived television adventure series called Manimal, about a man who could assume the form of various animals. The special-effects led show, which was also aired in Britain in 1984, preceded his appearance in the American soap Falcon Crest from 1984 until 1986.
Stealing Heaven (1988), based on the story of Abelard and Heloise, was a film which he co-produced with his second wife, Susan George. It was panned by The Daily Telegraph as "a dire medieval teen-pic", but MacCorkindale was already planning another film about the mysterious case of Lord Lucan, predicated on the earl's innocence. This project, for which MacCorkindale also wrote the script and in which he planned to star, was finally abandoned in 1996 after he fell out with the backers.
He joined the cast of Casualty in February 2002.
In 2006 MacCorkindale was diagnosed with bowel cancer, after complaining of feeling unwell while recording Casualty in Bristol. But his illness did not stop him taking a six-month sabbatical from the BBC at the end of that year to return to the stage for the first time for 20 years, when he joined a touring production of Agatha Christie's The Unexpected Guest.
In May 2007, contrary to previous indications, he was told that the disease had spread to his lungs, and that he had five years to live. He left Casualty later that year. But he refused to end his career, and in 2008 again returned to live theatre, appearing as Captain Georg von Trapp in a West End production of The Sound of Music. His last role was as Sir David Bryant in the television police series New Tricks.
"I don't want people to think that I'm pale, losing my hair, losing weight and on the way out," he said in 2009. "I'm not. I'm as active as I've ever been."
In the last year he spent much of his time with Susan George, whom he had married in 1984, at their 45-acre Georgian stud farm on Exmoor, where they bred Arabian thoroughbred horses.
Simon MacCorkindale married first, in 1976, the actress Fiona Fullerton. The union was later dissolved. There were no children of either of his marriages.