The Ace 0.5 cc diesel from London, England was made in relatively small numbers for Harry York, who owned the well-known London model shop Model Aircraft Supplies Ltd. of 171 New Kent Road, London SE1. It was apparently introduced as a "house model" for York's hobby shop - a not uncommon practise at the time. Production appears to have been confined to the years 1947-1948. It's extremely unlikely that the number manufactured came anywhere near reaching four figures. Despite its somewhat "agricultural" appearance, the engine is very well made where it counts and runs surprisingly well. A complete review of the Ace 0.5 cc diesel together with some actual test results may be found on Ron Chernich's "Model Engine News" (MEN) web-site.