The 1956 pattern boot was a big departure from previous flying boots, as the high ankle was worn inside the flying suit, whereas previous boots had widee openings and the suit leg would be tucked inside. This change is rumoured to help in a fire situation as the older boots could capture and retain spilt fuel; I am yet to find this documented though.
Quote:
135. Introduction. The 1965 pattern aircrew boot (Fig 27) was introduced to provide aircrew with a rugged item of footwear suitable for use in flight and in any survival situation.
136. Description. The boot consists of black leather uppers which are lined and bonded to a tough composition sole. The uppers are extended high on the ankle and are fitted with a foam padded rim for comfort. Fastening is by means of two rows of eyelets and laces. The underside of the sole is moulded into a non-skid, anti-FOD pattern. The leather of which the boot is constructed is proofed to provide the maximum degree of protection in a land survival situation.
137. Fitting Criteria. The 1965 pattern boot is available in 17 sizes (Medium and Large in 8 basic unit increment sizes from 5-12 plus a special fit size facility) and should be sized to give a comfortable fit ofer the thickest socks likely to be worn. It is usual to issue the 1965 pattern boot to fit over two pairs of terryloop socks or terryloop sock plus immersion sock Mk3 fitted to the immersion coverall Mk10.
138. The design and construction of the 1965 pattern boot is suitable for wear with either 'summer' or 'winter' AEA, although it is essential to wear this pattern of boot with the latter assembly.
These boots were well used when I acquired them, showing signs of service life. Since then I have used them for a bit of reenacting with classic jets.
Note how these boots have a very shallow and wide pattern tread, this is to help stop the boots carrying grit / stones into the cockpit, which could result in FOD. A lot of aircraft access ladders are also designed with brushes or fibre mats to wipe boots on before entering the cockpit.