-SG- Roger has done a lot of further digging into this matter following our posting re the 633 Track CS1 being restored by the Bain family. The first of his two very relevant messages is shown below:
"I did not doubt that the engine had been used in 633cc form but I did not accept that the Montlhery records were taken with it but in its 588cc form. However, in the light of the pictures of the frame which must have been part of the team, I decided to do some more digging.
I was puzzled as to why the flywheels would have been marked 633 as they would have been the same for the 588 engine as the only difference would have been the larger bore while the stroke remained the same. I have now found that there was a 665cc version with an even longer stroke and this would explain why there would be a need to mark the flywheels appropriately. This led me to look at other possible later events where the engine could have been used and I found that a 633cc Norton was entered by Nigel for Bert to ride in April 1928 meeting postponed to May. This fits in with the development work for the Montlhery records but as both the 588 and 633 versions were entered. Bert finished second in two races on a 588 so it appears that that the 633 was not used in 1928 and the 665 was also a non starter. There was a 633 Norton used for sidecar events which could well have been the CS1. I still don't understand the KENT lettering though!"
Here's an excerpt from the second of Roger's messages. For those not into Brooklands activities in the pre-war era, Parry-Thomas was a successful and innovative driver who lost his life in a world speed record attempt on the Pendine Sands driving his chain driven special 'Babs.' As Roger mentions, he also ran an engineering business at the track.
"I have a possible solution to the KENT stamp on the crankcase of the 633 CS1. Following the death of Parry-Thomas in 1927, Ken Thomson joined with Ken Taylor to take over the running of Thomas Inventions Ltd. - becoming Thomson and Taylor Ltd. Nigel Spring's accounts showed that they used Thomas Inventions for a lot of their engineering work which was not surprising as they were based at the track. It is likely that T&T carried out machining work on the crankcases of the Bain 633 engine ... The CS1 engine would have been put together in the spring of 1928 when the T&T company name had not been formally established so they were stamped KenT but all in uppercase as lowercase stamps are rare."