The Norton 16H is a designation given to British motorcycles made between 1911 through to 1954 with various modifications and refers to a single cylinder Norton 490cc side valve engine with a bore and stroke of 79 x 100 mm. The H denotes the Home model as distinct from the Colonial export model.[1] Norton was the main military motorcycle supplier prior to WW2 and one of the main suppliers of motorcycles to the British Army in World War II with a total of nearly 100,000 produced. British Army Nortons were also supplied to the Commonwealth forces such as Australian, New Zealand, India and the Canadian Army.
https://en.wikipedia.org/wiki/Norton_16H

The core engine was acquired in Germany. The parts needed to make it a complete engine came from Australia, Austria, Canada, Germany, the UK, and the USA. Other miscellaneous parts were sourced in countries not mentioned above.