In the last couple of years, I have seen a Bristol Gas Starter engine on a shelf in someone's workshop. It was designed & built by Bristol Aero Engines for assisting the starting of their big radials by providing ignitable mixture at above atmospheric pressure to the induction system.
One of the back issues of SEM (115) I picked up on Saturday has a photo of one at the NEVTEC rally in Claybrooke in June 1983, s/n 1129, the property of Malcolm Graham.
Regards,
Kim Siddorn