Electric torch in UK from the start.
The Hellesen type cell (Sweden) was copied by a British Chemist who patented it in the USA. A Novelty company bought the patent and sold electric torches to the NYPD. The batteries were poor, hence flashlight.
By 1905 they were as good as the Hellesen type and the company was variously Eveready, Union Carbide and NCC over the years. The UK branch was by 1905 the British Ever Ready Electrical Company, later Ever Ready. After WWII they used BEREC overseas and US NCC/UC/Eveready sold as UCAR. They agreed market areas. Eventually the US became Energizer and bought the UK Ever Ready company which had been asset stripped in 1980s to 1990s.
Sometimes US usage was used.
US Eveready 1923
US Novelty Company using Eveready brand in 1905
UK Ever Ready, before 1939. Refers to torches. Electric prefix already dropped.
UK Ever Ready in 1932 Torches and Batteries
Hellesen Advert 1930.
Wet or open zinc carbon batteries existed maybe from 1831, but Hellesen invented the sealed cell in Sweden, Copied by English chemist and patented in USA and bought by the American Electric Novelty & Manufacturing Company, later USA Eveready (one r), NCC, UC, Energiser. But inferior at first, hence NYPD "flashlights". That really got them started.
http://www.blaukatz.com/overview/
The NYPD nickname of Flashlight stuck in the USA. It was Electric Torch in UK from at least 1906.