THE last survivor of the RAF's early experiments in radar - crucial to winning the Battle of Britain - has died.

Air Marshal Sir Arthur McDonald was leader of the top-secret ``Biggin Hill Experiment'' and in 1937 was the first person to track and intercept a foreign plane using newly-invented radar.

Born in 1903, Sir Arthur had an exceptional and highly varied career. As well as pioneering the use of radar at Biggin Hill, he invented the ``Duxford flare path'', a system of landing lights that could not be seen by the enemy, sailed in the 1948 Olympics, and became the last British Commander-in-Chief of the Pakistan Air Force.

Lord Swinton, Air Minister during the late thirties, told him: ``I hope you young men realise that the whole future of this country depends on the results

of what you are doing here at

Biggin Hill.''

For having proved it was possible to intercept enemy aircraft using radar, a ground-to-air control system and radar chains were developed. Without them, it is highly unlikely the RAF would have triumphed in the Battle of Britain.

Later in the war, McDonald flew single-handed from Africa to Ceylon (modern-day Sri Lanka) and undertook responsibility for the air defence of the island.

At the age of 45 he represented Britain in the Olympics, as one of the last great amateurs. He was the oldest competitor sailing and refused to practice because that would have meant taking time off work.

He continued to sail, winning his last race at the Royal Lymington Yacht Club at the age of 92.

Air Marshal Sir Arthur McDonald KCB, AFC, DL died in his sleep on July 26 at Lymington, Hampshire.

He leaves a wife, Mary, two sons, and two daughters.