Gareth, It has come up a treat ! you will find it both near impossible and very expensive to obtain a genuine liner, there are plenty of repros around, but they will look out of place on a helmet such as yours. I would leave it alone, do not try to remove the band, the liner pins will probably break...and you will of lost some important originality, if you have to put pads in, leave the band as is, and simply push the leather of the pads down between the band and the helmet shell, using a thin bladed screwdriver, they will stay put, held on by tension/pressure of the band, originally the pads were crimped to the band. All helmets were mm (maker mark) and had a heat lot code in the inside dome. The mm is forward of the M91 chinstrap lug towards the front and will usually consist of 2 letters i.e. "ET" identifying the maker and 2 numbers indicating size, thes will be either 62 or 64 on your helmet. Rust may obscure these markings, lightly rub the area with a wet cloth, and see if anything appears. If you wish to source pads for display purposes, they will need to be "White" M17 type, see here...Military Reproductions ..........Prost ! Steve.