Bantamoto built bicycle engines from 1951 to 1952.
This was a cycle attachment manufactured in the Cyc-Auto works in Acton, London, and it attached to the rear wheel of a bicycle. The machine had a vertical cylinder 38cc (38x34mm) single-speed two-stroke engine, flywheel magneto, and petroil lubrication. The fuel tank was mounted above the engine. Transmission was by spur gears. It was stylish but expensive to make, so Cyc-Auto returned to producing their own range.
Sources: Graces Guide, cyclememory.org