Prewar saddle cover?

It was originally made of a 'leathercloth' names 'Rexine' which was a linseed oil based covering on a canvas backing. Unlike modern vinyl, it is not warm and 'soft' to the touch and has no stretch.

It doesn't seem to have been made in heavy grades since the 1970s (some tnin varieties were produced for bookbinders) and it doesn't store well, being prone to cracking and deformation.

The lack of avilability of Rexine is one of the great problems in obtaining a factory finish on post-vintage motorcycles. I wish that I knew of an answer.