-SG- Those with a longish memory may recall that the 1930 DT engine in Dunedin is fitted with a Polson piston. A further query has come up from Paul, who is working on a well-worn late forties Inter, which belonged to his father. A couple of Polson pistons were with the bike and Ian has been a big help - as usual - in identifying them. He has also sent scans of the 1955 Polson catalogue and the relevant page with Norton pistons listed on it. These scans are attached via this link and many thanks to Ian for providing them.
Incidentally he tells me Polsons started trading in 1927 - the name derived from the surnames of the founders, Herbert Pollard and Edward Nason. Pollard died in 1936 but Nason carried on in the business for many years. In 1951, Polsons was sold to one of it's competitors, ACL. ACL produced pistons, rings and other motor components, and in 1961 was sold to Repco, owned by Geoffrey Robertson. It appears that Jack Brabham approached Repco to develop the 5000cc racing engine, which was successfully done under Frank Hallam as Chief Engineer, and Phil Irving - who needs no introduction to the motor cycling world. It was always a sore point to Phil Irving that he and Repco never received credit for developing the engine that won two world championships. Jack Brabham took most of the credit as the driver/constructor.
After various company ownership changes, Polsons appear to have become part of the ACL-Mahle business - producers of the well-known Mahle piston range.