He served in the battleship Rodney and the cruiser Edinburgh in the South Atlantic and Indian Ocean, but his appointment to the battleship Prince of Wales was cancelled when his father was given command of her.Instead the young Leach went to the cruiser Mauritius, and when she went into refit at Singapore he became a plotting officer in the war room there.At his post he learned of the torpedoing of his father’s ship by the Japanese in the South China Sea on December 10 1941.

His advice was clear: the Falklands should be recaptured, “Because if we do not, or if we pussyfoot in our actions and do not achieve complete success, in another few months we shall be living in a different country whose word counts for little”.

Leach then explained to the Prime Minister that the ships would take three weeks to reach the South Atlantic.

When asked about the aircraft carrier Ark Royal, he pointed out that the old ship had been scrapped, under a previous administration; and that the new one, building at Barrow, would take two years to complete.

On March 31 1982 Leach returned from a visit to Portsmouth to London, where he read the intelligence and operational briefs about the Falklands circulating in the Ministry of Defence (or “the zoo”, as he called it).

The first predicted the certainty of an Argentine invasion; the second advised that nothing could be done.

Leach’s view was different: if Argentina invaded the Falklands, it was the Navy’s job to recover the islands.The Chief of the Defence Staff was on his way back from a visit to New Zealand, and — bypassing the Acting CDS — Leach sought out the Defence Secretary John Nott in the House of Commons, finding that the minister and his advisers were with Mrs Thatcher in the Prime Minister’s office, undecided about what to do.Nevertheless, his advice was that, even with only two small carriers to provide air cover, Hermes and Invincible, the Falklands could be recaptured and that the operation should proceed.This was greeted by the Prime Minister with relief and approval, and over the weekend a Task Force was prepared. Leach, who had been appointed KCB in 1977 and GCB in 1978, was promoted to Admiral of the Fleet when he retired from active service at the end of 1982.Henry Conyers Leach was born on November 18 1923, the third son of the future Captain JC Leach, MVO, DSO.He was educated at St Peter’s Court, Broadstairs, and joined the Royal Naval College, Dartmouth, in 1937.