Sleeve Length: 23" / Short - Label states a regular length

Chest Size: 48" | Suggested Size: X Large Slim - Label suggests a chest of "115-120"cm / "GrNr 20"

but there doesn't seem to be much information on this

Main thing to note is the marking on the front

British RAF Women's No. 5 Mess Dress Jacket - WRAF / PMRAFNS - Medium Ireland Sleeve Length: 23" / ShortAt a glance 100% Wool Body Single Button Closure Engraved "Staybrite" Buttons No. 5 Mess Dress Squadron Leader Matron Rank Cuff Laurels Bullion Princess Mary's Royal Air Force Nursing Service Sleeve Patch PMRAFNS Collar Badges Fully Sateen Lined Elegant Royal Air Force Grey Blue Colour Tailored by E. C. Snaith & Son Ltd. Excellent Tailoring Pit to Pit: 19" Suggested Size: Medium Slim Label recommends a chest of 92cm Sleeve Length: 25" Regular Label