As a three-time senior steward of the Jockey Club he was more enlightened than the stereotype of the ancient regime in racing would suggest. The appointment of women members to the Jockey Club, the introduction of starting stalls and the identification of the need for a more accountable way of running racing were just three of his measures.
Ironically, the most notable event in his life came far removed from the lush, verdant racecourses of England. Few men can claim they have been within inches of changing the course of world history in the way that Howard de Walden could.
As a languages student in Munich in the 1930s he knocked over a talkative artist and politician while driving, a man at the time known simply as Adolf Hitler. Even more astonishingly, Howard de Walden recalled in his memoirs, Earls Have Peacocks (1992), how he sat in a box next to the Fuhrer's at the opera and leant across to introduce himself on a more formal basis than their previous encounter. Hitler recalled being run over "and was quite charming to me for a few moments".
He was born John Scott-Ellis, with a twin sister, in 1912. His interest in horseracing was stirred at an early age. His father, Tommy, the eighth Baron Howard de Walden, was himself a keen owner of racehorses and had purchased the illustrious bloodstock of Major McAlmont in 1901. The young John became truly bitten by the sport when convalescing near Newmarket from a bout of measles. Early morning trips to the gallops would see him secure tips for the day's racing from several jockeys.
His father also had literary interests; at one point he owned the Haymarket Theatre, where he used to stage plays by Ibsen and other great European playwrights, and he was friendly with Bernard Shaw, G.K. Chesterton and Hilaire Belloc. It was the painter Augustus John who was responsible for the family's famous silks. He told Tommy that apricot would be an appropriate, distinctive colour to offset the green of the turf and thus be easily recognisable from other silks. John Howard de Walden later noted wryly that the distinctive nature of the apricot silks was an irritating aid to the handicapper when assessing the runs of his horses and thus what weights they should carry in future races.
As a child John began his education at Eton one year earlier than he should have done. With his father serving in the First World War the entry to the school was made by his mother - "Mathematics was not her forte," he later said. After that, spells in Munich and in Kenya, where his father had farming and newspaper interests, followed, before he went up to Magdalene College, Cambridge. He was also sent to Spain to check on the whereabouts and health of his sister Priscilla, who had volunteered for nursing duties during the Spanish Civil War.
Much of his time during the Second World War - when he was commissioned in the Westminster Dragoons - was spent in Canada, where he was an instructor at the Canadian Staff College in Ontario. While disappointed at such an unglamorous, cold, posting, he also expressed relief that "nobody was shooting at me, so I suppose I should have been grateful".
After the war, an attempt to resurrect a previously uninspiring shipping business in South America was aborted with the death of his father from cancer in 1946. He inherited from him the extremely valuable Marylebone estate - 100-odd acres of central London between Oxford Street and Marylebone Road - passed down from his great- grandmother, Lady Lucy Cavendish-Bentinck - along with 8,000 acres in Ayrshire and the island of Shona on Lake Moidart, as well as African and North American holdings.
His father had dramatically scaled down his racing interests in the 1930s, so John had to build up his own bloodstock empire from scratch. His first winner was a horse called Jailbird, a winner at Chepstow in June 1949. But he soon turned to the purchase of fillies in order to set up his own band of broodmares. He bought the Plantation Stud in Newmarket in 1958, and later the Thornton Stud in Yorkshire - that deal was a condition of his acquisition of several choicely bred mares owned by the late Sir Victor Sassoon.
One of his first successful broodmares was a filly purchased for 8,000 guineas at Doncaster sales - Sanlinea, called after the telegraphic address of his shipping line in South America. She went on to be third in the St Leger, the final of the five Classic races for three-year-olds every Flat season. At stud, she produced Amerigo, who won the prestigious Coventry Stakes at Royal Ascot. Other top horses from the early 1960s were Entanglement, Panjandrum and Oncidium. The latter colt as a three-year-old won the Lingfield Derby trial before he disappointed in the 1964 Derby. Switched from Newmarket to the more private training estate of Manton, in Wiltshire, Oncidium won the Coronation Cup, a major prize, before flopping in the Ascot Gold Cup in which his owner was convinced he was doped.
Few horses have better represented their owner than Kris, a son of a "quite useless" racemare called Doubly Sure, who was shrewdly sent by Howard de Walden's racing manager Leslie Harrison to the stallion Sharpen Up. Although surprisingly beaten in the 2,000 Guineas, Kris won 14 of his 16 races and was a top-class miler. He has also proved to be an outstanding a stallion, as has his full-brother Diesis, who two days after his owner's death supplied the winner of the Irish Oak in Ramruma.
The shrewd approach to bloodstock dealing was also demonstrated with the purchase of a German mare called Sayonara. She was purchased, again by Harrison, as a quality but "exotic" outcross to a particular line of stallions. Sent to Mill Reef, she produced a talented filly in Sandy Island; sent to Mill Reef's son Shirley Heights she produced the seven-length 1985 Derby winner, Slip Anchor. To win the world's most famous Classic meant a lot to Howard de Walden, who also owned a top National Hunt horse, the ill-fated 1974 Champion Hurdle Lanzarote. He was later killed in the 1977 Gold Cup.
After his first wife, Nucci, died of leukaemia when he was 63, Howard de Walden found himself engaged again in bizarre circumstances three years later. Late for a lunch date at York races where he was seated next to the Queen, he blamed his tardiness on the traffic. Sensing that this explanation was not entirely accepted, he then prematurely claimed he was late because he had got engaged to Gillian, Viscountess Mountgarret. They married soon afterwards.
John Osmael Scott-Ellis, racehorse owner and breeder: born Chirk, Denbighshire 27 November 1912; succeeded 1946 as ninth Baron Howard de Walden and fifth Baron Seaford; Senior Steward, Jockey Club 1957, 1964, 1976; married 1934 Countess Irene Harrach (died 1975; four daughters), 1978 Gillian, Viscountess Mountgarret (nee Buckley); died London 9 July 1999.