Holmes founded his electrical business in Portland Street, Newcastle, in 1883, in which year he installed electricity in his father's house, Wellburn, in Jesmond, which thus became the first electrified house in the city. It was while working on the New Wallsend Cafe that he invented the familiar quick-break electric switch action. He patented it in 1884 and in the following year, he made his first dynamo. The 'Castle' as he called it, was supplied to customers all over the world. Holmes also worked on train lighting sets, the electric drive of printing presses and the portable lighting sets used on the Suez Canal for navigation at night.
As well as being a pioneer, he was an extremely skilful and accurate craftsman. His workshop, a marvel of precision and methodical arrangement, is now on display at Newcastle Discovery. H.R.H. Holmes and Co. was eventually incorporated with A. Reyrolle in 1928.