This vintage jacket was made in 1955 by Prices Tailors Ltd to the 1949 Battledress Pattern. It is a British Army size 13, for someone 5’11” to 6′ with a 39-40″ chest. By the measurements, it is pretty oversized.
Chest (pit to pit): 24″ (doubled = 48″)
Shoulder to shoulder: 19″
Sleeve (shoulder to cuff): 27″
Length (base of collar to hem): 23-1/2″