Lord Lyon was foaled in 1863 at Oakley Hall, the stud farm of General Mark Pearson which was located twenty miles outside of Oakham in Northamptonshire.

In 1864, she foaled Lord Lyon's full sister, Achievement, which won the 1867 St. Leger, Doncaster Stakes and Coronation Cup among many other races.

[6] Lord Lyon was a bay horse that stood 15.3 hands high with "good bone, flat feet and very short pastern joints"[8] and had four white socks.

According to Charles Gregory, trainer James Dover's groom, General Pearson was "a hard man with his yearlings" and wanted "to know the best or the worst of them" as soon as the horses began training.

[4] Consequently, the yearling Lord Lyon was walked by Gregory 17 miles in the rain from Oxford to Ilsley to be trained by James Dover in early autumn 1864.

Lord Lyon trained on favorably over the summer of 1865 and was tried a third time on 3 August in a three quarters of a mile race on Ilsley Downs where he beat his three-year-old half-sister Gardevisure by seven lengths while only breaking into a canter.

"[15] In September at the Newmarket meeting, the connections of the filly Mineral (later the dam of the 1876 Epsom Derby winner Kisber) forfeited 200 sovereigns to Lord Lyon after backing out of a match race.

[13] On 11 October, Lord Lyon won the 7-furlong Troy Stakes at Newmarket while carrying 122 pounds, beating the Duke of Beaufort's colt Mr. Pitt by a margin of three quarters of a length.

[16] At his last two-year-old engagement at Newmarket, Lord Lyon won the Criterion by two lengths from the colt Young Monarque while carrying 127 pounds.

Custance persevered however and Lord Lyon responded to catch the Bribery Colt in the last strides and win by a head with Rustic three lengths back in third.

[22] At Doncaster in September Lord Lyon defeated Savernake "by sheer gameness and stamina"[23] in the St Leger, winning by a head after what was described as one of the most exciting races seen in many years.

[27] In March, Lord Lyon won the Trial Stakes held at Northampton, beating the colt Moulsey "with the greatest ease"[28] and winning £120.

[30] For the 1875 season, he was moved to Shepherd's Bush, a stud farm in London which was located three miles from Albert Gate[31] (an entrance to Hyde Park), for a fee of 26 guineas per mare.

[34] Lord Lyon's success at stud was hampered by chronic foot and leg ailments that stemmed from poor limb conformation.

The Earl of Suffolk remarked on Lord Lyon's condition in 1884, "he was in most respects as perfect a model as one could wish to see, but below the knee he dwindled away to nothing; his ankles were small and bullety, his pasterns straight, and his feet half the size they should have been.