Who was the only reigning British monarch to own a Derby winner?

In short, the only reigning British monarch to own a Derby winner was King Edward VII. He did so on May 26, 1909, courtesy of Minoru, trained by Richard Marsh at Egerton House Stables in Newmarket and ridden by Herbert Jones.

Having won the both the Greenham Stakes and the 2,000 Guineas at Newmarket en route to Epsom, Minoru was sent off as marginal second-favourite for the Derby. In an eventful renewal, which saw the favourite, Sir Martin, stumble badly and unseat his jockey rounding Tattenham Corner, Minoru fought a ding-dong battle with Louviers throughout the last quarter of a mile and the pair flashed past the winning post together. In the days before the photo-finish camera, an agonising waited ensued, before the judge eventually declared Minoru the winner by a short-head.

Prior to his succession to the British throne, following the death of his mother, Queen Victoria, on January 22, 1901, Albert Edward had already bred and owned two Derby winners during his lengthy tenure as Prince of Wales. The first of them was Persimmon in 1896 and the second Diamond Jubilee in 1900. Both horses were trained, like Minoru, by Richard Marsh.

For the record, the late Queen Elizabeth II won all the British Classics bar the Derby and came close to winning the ‘Blue Riband’ event more than once. On June 6, 1953, just four days after her coronation, Her Majesty witnessed her first runner in the Derby, Aureole, ridden by Harry Carr, finish second of 27, beaten four lengths, behind the favourite, Pinza, ridden by Sir Gordon Richards. On June 4, 2011, Carlton House, ridden by Ryan Moore, was sent off favourite for the Derby, but could find no extra in the closing stages and eventually finished third, beaten a head and thee-quarters of a length, behind Pour Moi and Treasure Beach.