The main reason for their popularity is the wonderful teddybear like liner which lines the entirety of the coat

there are button adjustable wrist cuffs as well as an internal torso drawstring

Hidden Button Closure

a bit more wear on the heel as shown

British Army WW2 Service Dress Jacket - Royal Artillery - Medium Field Shirt The main reason for theirAt a glance 100% Wool Material 2 Chest Pockets, 2 Waist Pockets & Internal Button Closure Engraved Royal Artillery Brass Buttons Military Cross, Star Medal 1939 to 1945, France and Germany Star Medal, Defence Medal, War Medal 1939 to 1945, Queen Elizabeth II's 1953 Coronation Medal & Efficiency Decoration Medal Ribbon Bar Lieutenant Colonel Rank Epaulette Pips Badges Grenade Collar Badges Manufactured by Hawkes & Co of Savile Row Shoulder Epaulettes