He settled in Miles City, Montana, before coming to Big Horn, Wyoming, and purchasing the Canyon Ranch in 1895.

[4] In 1899, he partnered with his neighbors, fellow British expatriates William and Malcolm Moncreiffe, in an expanded horse business.

Wallop and his partners bought horses at relatively inexpensive prices, trained them, and sold them to the British cavalry for as much as ninety-seven dollars.

[1] His granddaughter Jean Margaret Wallop, born in Big Horn, Wyoming, married Henry Herbert, 7th Earl of Carnarvon, whose seat was Highclere Castle.

She was close friends with Queen Elizabeth II, who is godmother to his great-grandson George Herbert, 8th Earl of Carnarvon.