When the First World War ended, Tomkinson remained in the army and commanded the Blues and Royals from 1919 to 1923. One of the best polo players of his time, he had captained the team that famously won the 1914 International Polo Cup. In 1921, he had another opportunity to represent England at polo, but this time it was the American team that won the cup.
On finishing command of the Blues and Royals, Tomkinson returned to India, where he had served before the war, to command the 3rd Meerut Cavalry Brigade from 1924 to 1927. Horse sports remained his passion and, although he suffered from the effects of a shoulder injury, he played polo regularly in Meerut and in outside tournaments, whenever his duties permitted. He was also in high demand as umpire being known as he was for his firmness and quick decision. In 1927, he once again made his way to America to seek the International Polo Cup, this time not as a player but as manager of the Army-in-India team. However, the American team held fast to the trophy.
Having retired from the army in 1927, Tomkinson remained in India to serve for a time as a stipendiary steward of the Royal Calcutta Turf Club, the country’s premier horse racing organization. His duties took him all around Northern India. The knowledge he gained of the finer points of racing stood him in good stead when he returned to England, where he rode many winners of National Hunt flat races.
In January, 1932, Tomkinson was appointed as manager of King George V’s racing and breeding studs. During this time he had an annual sporting bet of two shillings and sixpence with Sir Philip Hunloke, sailing master of the King’s yacht, Britannia. The winner of the wager was decided on the question whether Britannia provided the King with more victories in yacht racing than the Royal horses achieved on the turf.
Henry ‘Mouse’ Tomkinson died in a London nursing home shortly after midnight on 21 January 1937 at the age of 55, having been ill for some weeks. He never married.