Already learnt the price from the Morgan three wheeler Yahoo group (self interest declared here, I'm the so called 'owner').
Discussion on this car on that group suggests it may be less original than it appears. On finding out the registration number, I did a DVLA check and they have it as an April 1926 car. Super Sports Aero came out in October 1926 with a different and quite distinguishable chassis.
Somebody else checked the Morgan three wheeler club records, and the chassis number there is way too high. I've thought of a possible explanation of that, if the car is genuine; essentially a mis-read of handwriting could explain that point.
Another expert has looked and pronounces the bonnet section a flawed reproduction.
Not in our eyes worth £40k but whether somebody will pay that is another matter. As I said at the start it looks like a Oct, Nov, Dec 1929 car, but whether it actually is, would need to be determined.