The world of racing is mourning the death of leading owner and breeder Sheikh Maktoum Rashid Al Maktoum.
Sheikh Maktoum helped revolutionise British racing
The ruler of the emirate of Dubai is believed to have suffered a heart attack while visiting Australia.
He was co-owner of the Godolphin stables, a powerhouse in racing both in Britain and around the world.
"It's absolutely awful," said his racing manager Joe Mercer, adding Maktoum's family had "done a remarkable job for English racing".
"He really enjoyed his racing," Mercer said. "He knew what was going on and was a very good man to work for. He was a good loser and a good winner.
"He had 10 trainers throughout the world including Sir Michael Stoute, Ed Dunlop, Barry Hills, Mark Johnston, Andre Fabre and Criquette Head in France, and Neil Drysdale in America.
"He had over 200 horses in training and a lot of yearlings still to come in."
Along with brothers Sheikh Mohammed and Sheikh Hamdan, Sheikh Maktoum revolutionised British racing by pumping large amounts of money into the sport.
They also created the Dubai World Cup, the world's richest race which carries a purse of $6 million (£3.4m).
Sheikh Maktoum was the owner of Gainsborough Stud in Newmarket, where many of his stallions were stood after their racing careers.
He owned several Godolphin big-race winners including Balanchine, Cape Verdi, Fantastic Light and Shamardal.
"Sheikh Maktoum's death is a huge loss to Dubai but also to the world of horse racing. He was at the very centre of everything Godolphin has achieved," said the stable's racing manager Simon Crisford.
His best horses outside Godolphin included Cadeaux Genereux, Green Desert, Touching Wood, Shadeed, Hatoof and Royal Applause.
Johnston expressed his regret at the news and acknowledged Sheikh Maktoum had helped to put his yard at Middleham on the map.
"Obviously it's a great shock," said the trainer. "It's terrible and unbelievable and I had no inkling anything was wrong with him.
"He did a huge amount for racing, not just in Dubai but worldwide.
"Along with Sheikh Mohammed, he was instrumental in changing the whole shape of my yard and helping move me to a different level."
Ed Dunlop, who is employed by and based at Gainsborough Stables, expressed a similar sentiment.
"It's very sad news, primarily for Sheikh Maktoum's family and all of Dubai," said the Newmarket trainer.
"He was a wonderful man to work for and most importantly, he was the one who gave me a chance."
Sheikh Maktoum was elected an honorary member of the Jockey Club in 1985 and Julian Richmond-Watson, senior steward of the Jockey Club, was among those who paid tribute.
"Sheikh Maktoum Al Maktoum made a hugely significant contribution to the sport of horse racing and British thoroughbred racing and breeding in particular," said Richmond-Watson.
"The majority of his racing interests were based in this country and I believe he shared with the British racing public a love of horses, of racing and of the history and heritage the sport has in this country."
The A1 Grand Prix championship has postponed its races at Sentul in Indonesia on 15 January following the death of Sheikh Maktoum.
The series was devised and paid for by another member of Dubai's ruling
family, Sheikh Maktoum Hasher Maktoum Al Maktoum, whose father was a cousin of the Emir.