Well someone’s got to stick their neck out and get the ball rolling
My understanding is as follows:
The works prototype was raced from mid-1956, usually by Salvadori but once by Brabham
Three more cars were completed for the Oulton Park Gold Cup race at the end of September. These were a second works car for Brabham, one for Rob Walker, which Brooks drove, and a private car for Ken Wharton. All four cars used 1½-litre Coventry Climax FWB engines.
Next off the production-line were two cars supplied to New Zealanders Ronnie Moore and Ray Thackwell for racing in South Africa (with 1100cc FWA engines) in March/April 1957
And one or two more may have been built for the Cooper Racing Drivers’ Training School