Horses, like dogs, were the Queen’s lifelong love.
Whether it was racing thoroughbreds or ponies, she showed an unfailing interest.
If one of her horses was running, the Queen would watch and become more and more animated.
She was known to sometimes jump up and down in excitement as the race progressed.
When her horse was first to cross the line, she was ecstatic.
Her introduction came at the tender age of two when, in the autumn of 1928, she accompanied her parents to Naseby Hall in Northamptonshire for the hunting season.
Such was her fascination, she used to run off to the stables at the slightest excuse at any time of day.
From early childhood, she was surrounded by horses and relatives who owned, rode and talked about them.
Elizabeth, like many aristocratic young girls, became a keen rider.
Her first reported riding lesson took place in the private riding school at Buckingham Palace Mews in January 1930, when she was just three years old.
When she was five, her mother led her on Peggy – a Shetland pony given to her when she was four by King George V – to a meet of the Pytchley Hounds.
In 1938, riding instructor Horace Smith began giving Elizabeth and her sister Margaret twice-weekly lessons at the palace.
Elizabeth not only enjoyed riding but she also liked looking after horses and her passion became almost an obsession.
On one occasion she told Mr Smith that “had she not been who she was, she would like to be a lady living in the country with lots of horses and dogs”.
It may have been, of course, that animals were a substitute for other children as the princess grew up during a privileged, but isolated, childhood.
Animals would also have been unconscious of rank and, unlike human beings, could receive royal emotion without comment.
The Queen’s cousin, Margaret Rhodes, described how important the animals were to her when she acceded to the throne.
“You see, I think that early on, when she became Queen, I think that she had to sacrifice within herself an awful lot of emotions and thoughts of the future and everything else,” Mrs Rhodes told the BBC One documentary The Queen: A Passion For Horses.
“But I think with horses it’s another world in that it reduces you to just the person in relation to the animal, and you’re not a queen, you’re just a human being.”
Riding lessons had continued throughout the 1939-45 war and, with future troop-reviewing in mind, Mr Smith taught Elizabeth to ride side-saddle.
In 1943, she won first prize at the Royal Windsor Horse Show for driving a utility vehicle harnessed to her black Fell pony – a trophy she won again the following year.
Watching racing was a developing interest, as well as riding and driving, and in the spring of 1942 she was taken by her parents to the Beckhampton stables on the Wiltshire Downs where horses bred at the royal studs were trained.
In particular, they went to see two royal horses, Big Game and Sun Chariot, which were strongly fancied for the Derby and the Oaks.
Visits to see the mares and foals at the royal stud at Hampton Court, and to see the horses in training at Newmarket followed.
After 1945, the horse world became Elizabeth’s chief relaxation and escape, and she was to expand her interest in horse management and breeding.
Horse breeding was a family pursuit. The royal studs had been founded at Hampton Court in the 16th century, later moving to Windsor.
In the late 19th century, the then-Prince of Wales, later Edward VII, had established the Sandringham stud.
For her part, in 1962, Elizabeth, now Queen, leased and later bought Polhampton Lodge Stud, near Overton in Hampshire, for breeding race horses.
In the late 1940s she received the filly Astrakhan as a wedding present from the Aga Khan.
She acquired her own racing colours in 1949 of scarlet with purple hooped sleeves and black cap, when she and her mother jointly bought the steeplechaser Monaveen.
Monaveen was the first winner in the princess’s colours in the Chichester Handicap Chase at Fontwell Park, on October 10 1949.
When she acceded to throne in 1952, the Queen inherited the royal colours: purple with gold braid, scarlet sleeves, black velvet cap with gold fringe.
The Queen’s first winner as monarch was Choir Boy in the Wilburton Handicap at Newmarket on May 13 1952.
In 1954, the Queen’s horses, including Aureole, were so successful that she was the leading winner-owner. She repeated the triumph in 1957.
The high performance of the 1950s, however, could not be maintained and the 1960s was a decade of decline.
In May 1967, the Queen made the first of two private trips to France to see studs.
Later, there were similar private royal missions to the United States.
In 1969, Lord Carnarvon, the Queen’s close friend with whom she shared a passion for horses, became her racing manager, and royal racing and breeding fortunes greatly improved.
The 1980s and 1990s saw a mixed performance, and royal investment in the turf was regarded as secondary compared with the vast sums spent by Arab owners.
The fortunes of the Queen’s horses were said to have been hampered by her inability to use Irish-based stallions because of the political climate at the time.
In 2001, the Queen was devastated when Lord Carnarvon died of a heart attack on September 11.
Even in her later years, the Queen loved to ride and did so whenever she could, at Windsor, Sandringham and Balmoral.
In 2003, at the State Opening of Parliament, the Queen showed she had racing on her mind when she announced details of a Bill about the “National Hunt Service” rather than “health service”. She quickly corrected the slip of the tongue.
The Queen had won every classic except the Derby.
She came closest in her coronation year of 1953 when Aureole was second. Her horse Carlton House came third in 2011.
In 2008, she had her first Ascot winner for nine years, crying “I’ve done it”, when her horse Free Agent won the Chesham Stakes.
It followed Blueprint’s victory in the Duke of Edinburgh Stakes in 1999.
In 2013, the Queen’s horse Estimate claimed victory in Royal Ascot’s Gold Cup – the first time in the race’s 207-year history that it had been won by a reigning monarch.
A delighted Queen clapped her hands in excitement and beamed as she watched the race alongside her racing manager, John Warren.
Her grandson Peter Phillips told Channel 4 at the time: “It’s amazing, this is her passion and her life and she’s here every year and she strives to have winners.
“To win the big one at Royal Ascot means so much to her. Everyone is just thrilled, it’s very close to her heart and today is very special.”
A year later Estimate was runner-up in the same race, but went on to be stripped of its second place position after testing positive for morphine.
The post-race sample was the result of a contaminated batch of feed and the Queen’s trainer, Sir Michael Stoute, did not face a financial penalty.
In November 2014, the Queen was given a lifetime achievement award for her devotion to equestrian sport by the Federation Equestre Internationale (FEI).
Princess Haya Bint Al Hussein of Jordan, the outgoing FEI president, said at the time: “She is a true horsewoman, who still rides whenever state business allows, and her knowledge of breeding and bloodlines is incredible. The bond between the Queen and horses is truly extraordinary.”