Vice-Admiral Sir Alastair Ewing

Under Ewing, Offa took part in the Commando raid on Vaagso in northern Norway in December 1941, and escorted 10 convoys to and from Russia, including convoy PQ 17 in July 1942.

PQ 17 had lost four ships to heavy air attack, but was still in good heart and good order when, on July 4, the First Sea Lord, Admiral Sir Dudley Pound, deduced from Ultra special intelligence that the German battleships Tirpitz and Admiral Scheer were about to sail from their Norwegian base and attack PQ 17. Over-ruling the advice of his intelligence staff, Pound sent three urgent signals, the last of which read: ''Convoy is to scatter.''

Such an order, normally only given by a commander on the spot and in the face of imminent danger, horrified Ewing and his officers. Everybody on Offa's bridge saw the look on Ewing's face as he signalled ''God be with you'' to the nearest merchantman, while Offa hauled away westward at full speed with the rest of PQ 17's destroyer escort.

More than one of Offa's officers urged Ewing to disobey the order and turn back. But, to Ewing, an order was an order, and judging by the urgency of those signals, Tirpitz might appear over the horizon at any moment. So Offa stood on, and soon began to hear the first cries for help from merchantmen being attacked by U-boats and aircraft. In all, PQ 17 had 23 ships sunk. Tirpitz and Scheer did sail the next day, but came nowhere near the convoy.

Robert Alastair Ewing was born on April 1909, the son of Major Ian Ewing, of Mount-hooly, Jedburgh. He joined the Navy as a cadet at Dartmouth in 1923, and served before the war in the battlecruiser Hood, and the destroyers Vanquisher, Valorous, and Shamrock. In 1937 he joined the new destroyer, Imogen, as first lieutenant and was mentioned in despatches after she and the Ilex sank a U-boat in October 1939. His first command was the hunt-class destroyer Cattistock, operating in the 21st Flotilla, in the Channel and along the east coast. Ewing was mentioned in despatches again in 1941.

After the war, Ewing commanded the new destroyer, Cheviot, for two years in the First Flotilla in the Mediterranean. He then had appointments in the Admiralty, on the staff of the Second Sea Lord, and in Washington DC on the Nato staff. He took over at short notice as captain of the battleship Vanguard and commanded her at the 1953 Coronation Review at Spithead.

His last sea-going appointment in 1958 was as Flag Officer Flotillas (Mediterranean). Ewing had been expected to rise to the top of the Navy, but his final appointment, from 1960 until he retired in 1962, was somewhat low-key - Admiral Commanding Reserves and Inspector of Recruiting. He was appointed CB in 1959, and KBE in 1962.

On Offa's bridge, with his height, brilliant blue eyes, and black furry Russian hat inherited from his grandfather, Ewing cut a striking figure. He had tremendous physical and mental stamina, able to keep his concentration for days, with only occasional snatches of sleep, despite the bitter Arctic weather. Years later, officers and men who served with Ewing still remember him as the best captain they ever had.

In retirement, he moved to the United States, where he dealt in real estate and became a yacht broker in Florida.

As a member of a distinguished Borders family of sailors, soldiers, lawyers, and landowners, Alastair Ewing was very proud of his Scottish ancestry. He took a close interest in his local family history, which goes back in the Jedburgh, Selkirk, and Melrose area for some 300 years. He was also the historian of the Jed Forest Club, which has been described a ''a Hunt Club without the hunt'', and transcribed some of its nineteenth-century journals for a modern readership.

He married first, in 1940, Diana Archer, who died in 1980. They had a son. He married secondly, in 1984, Anne Chichester, daughter of a naval officer and also widow of a Navy officer. he first met Anne when he was a cadet at Dartmouth.