I think the car was originally built in 1955. It was Percy Crabb's car, which had a Bristol engine, and was registered 8APH. The car was fitted from new with Dunlop "D-type" wheels, hence the earlier question. A later owner obviously decided he wanted more power, although I think I read somewhere that this is an engine from a DB2/4, which can't have made a lot of difference.
Here's a photo of the car in 1955 (?) with Bristol engine - it may have been a previous AP puzzle. The caption says 1956 but I think it may be wrong.