did a little googling around (since when is googling a word?) and found a batch of engines at an auction.. with this comment under "lot 59" in the link:

Very mixed lot included big water cooled glow [ED Miles Special, I believe. rc], an OS pull start unit for car or boat, a Cameron 15 geared engine, early ign engine, £200

http://modelenginenews.org/deRancoug....html#P1190029

So perhaps a Miles Special?