The H-P range of model engines from Barnet in England was a successor line to the earlier Atlas spark ignition models which had been manufactured in Studham, near Dunstable in Bedfordshire. The H-P line-up included both spark ignition and diesel models, all of which were sideport units. 

The manufacturers of the H-P engines were a company called Henleystone Products of Barnet, just to the northwest of London. The range was marketed by a company called Morbone Requisites, who were also located in Barnet. The engines were built to extremely high levels of quality and ran very well by the standards of their introductory period.

Despite their worthy qualities, the H-P engines had a relatively short marketing tenure extending from early 1947 to early 1949. This was due both to the engines' high prices and to the failure of the manufacturers to develop new and improved designs to keep pace with developments from other competing firms. As the H-P engines became increasingly outdated and overpriced, demand for them evaporated, forcing them off the market.

Full details of the H-P range may be found in a detailed article elsewhere on this web-site.