Whereas the Mk II Oliver Tiger was adapted from the original very succesful range of tethered car engines, the Mk III was purpose designed for aeromodelling use. Not only (to my eyes at least) was the Oliver Tiger Mk III one of the most beautiful engines ever made but it was also a very easy engine to start and to handle. It was very successful as a competition engine and demand always outstripped supply.
This engine is fitted with an ETA prop nut rather than the one it would have been supplied with.
The serial number has been edited out of this photograph