After WWII, David Brown improved the VAK1 tractor, calling it the VAK 1A, built from 1945-1947, until it was finally became the David Brown VAK 1C, Cropmaster in 1947, with all the VAK 1's problems ironed out. The David Brown Cropmaster was made between 1947 and 1954, and nearly 60,000 of these were made. The petrol/TVO Cropmaster produced 35bhp, but in 1949, David Brown started making the diesel that was slightly more powerful, at 31.5bhp. The Cropmaster is capable of nearly 18mph in top gear.
The Super Cropmaster was a development from the Cropmaster. Introduced in 1950, and made until 1953, there were less than 5000 built, making them quite rare. The engine bore size had been opened up from 3 ½" to 3 5/8", delivering more power. The Super Cropmaster had vertical vented engine panels a higher engine speed. 12 volt electrics were standard. A dome topped pre-air cleaner, as with diesel models were also standard. Larger mudguards and oversize tyres were also standard.
Ref: Farm Classics, Volume One. David Brown Tractors 1936-1964 by Alan Earnshaw