His mother was Princess Beatrice of the United Kingdom, the fifth daughter and the youngest child of Queen Victoria and Prince Albert.

In the United Kingdom, he was styled His Highness Prince Leopold of Battenberg under a royal warrant passed by Queen Victoria in 1886.

Leopold was commissioned a lieutenant (supernumerary) on 16 October 1909 in the 8th Battalion of the Isle of Wight Rifles, a Territorial Force unit.

[9][10] He resigned his commission on 14 April 1920; at the special request of his cousin, George V, he was granted the honorary rank of major.

[12] Under a further warrant in September 1917 he was granted the style and precedence of the younger son of a marquess, and became Lord Leopold Mountbatten.