After World War II Morgan had re-introduced their 4/4 model fitted with a 1267 cc Standard engine. This continued in production until 1950 when it was replaced by the larger Plus 4 announced at the 1950 Earl's Court Motor Show.

The Plus 4 at its introduction was fitted with a 2088 cc engine based on that used in the Standard Vanguard, installed on a strengthened 4/4, chassis with a wheelbase lengthened by 4 in (102 mm). Hydraulic brakes, at first all drum, were fitted for the first time on a Morgan.