Major Bruce Shand, who has died aged 89, was famous for keeping his cool: this earned him two military crosses in the second world war and, half a century later, the gratitude of the Prince of Wales for keeping quiet - in public, though not in private - when Charles began an illicit affair with Shand's daughter Camilla, now the Duchess of Cornwall.
During more than a decade of lurid headlines, there were rumours of confrontations between Shand and Charles over Camilla's status, before the couple married in April 2005. As one long-standing friend put it: "I think [Shand] was completely frank with him, but they never came to blows." There was a strong bond between father and daughter, and Shand could not tolerate Camilla being treated shoddily.
One reported instance of his intervention was in 1993, after the disclosure of intimate taped phone calls between the lovers. At a private meeting, Shand reportedly reproached Charles for ruining his daughter's life, reducing the prince to tears. Conversely, throughout the divorce from Princess Diana, he was said to have been a tower of strength to both Charles and Camilla. Charles grew "very fond" of his father-in-law, admiring his courage, wit and impeccable manners.
Shand's father, Philip Morton Shand, was an architectural writer and critic, and an authority on food and wine. His company imported Alvar Aalto's furniture to Britain, and he counted among his circle such leading architects as Walter Gropius, Le Corbusier and Wells Coates. His marriage to Edith Marguerite Harrington ended in divorce when Bruce was three. Philip went on to acquire three more wives; his youngest child grew up to be Elspeth Howe (Baroness Howe of Idlicote), though Bruce met his half sister only when she was 16, and, indeed, 15 years were to pass after his parents' divorce before he again encountered his father.
He had a peripatetic childhood, being raised partly by his mother and stepfather, and by his Shand grandmother, to whom he was devoted. He was sent to Rugby school, which he found oppressive, but developed a love of horses and riding. He went on to Sandhurst, was commissioned in the 12th Lancers as a second lieutenant in 1937, and indulged his interest in hunting and polo.
In his self-deprecating memoir, Previous Engagements (1990), Shand recalled how he went to war in 1939 wishing he could have emulated a young officer from his regiment who had set off to fight the Boers in a hansom cab, having been at a splendid party in London the night before. The reality was very different. Seven months after mobilisation, he was in St Omar, northern France, facing the Germans in their drive towards the sea. He pulled back with his men to the coast, and narrowly avoided capture before evacuation from Dunkirk. Typically, his memoir does not mention the MC, though the citation spoke of his "skill and great daring" and how, by "the fearless manoeuvring of his troop, he covered the withdrawal of a column in the face of fire from four enemy tanks".
By 1942 Shand was in North Africa. The battle of El Alamein was raging and, promoted to major, he was ordered to slip through the enemy's retreating frontline on a reconnoitre. Heading down an escarpment, he was confronted by a German motorised column, which engaged his men in heavy fire. He managed to withdraw a group of the 6th Rajputana Rifles and organised the evacuation of 20 armoured cars, which would otherwise have fallen into enemy hands. The citation to his second MC said he had constantly proved himself a cavalry leader of "the first order". Wounded, he was taken prisoner and spent the rest of the war as a PoW.
Shand returned to Britain in 1945 to marry Rosalind Cubitt, the daughter of Lord Ashcombe, whose builder ancestors had created large swathes of central London, including Belgravia and Pimlico. After dabbling in various enterprises, Shand settled into a comfortable life as a partner in a firm of Mayfair wine merchants. He was vice lord lieutenant of East Sussex (1974-92), a deputy lieutenant of the former county of Sussex and joint master of the Southdown fox hounds (1956-75).
His wife died in 1994; he is survived by two daughters and a son.
· Bruce Middleton Hope Shand, soldier, born January 22 1917; died June 11 2006