Thanks for the thoughts folks.
I am due to visit the local ye olde leather shop, so we might see what they say.
I do have a neatsfoot oil story.
Was in the garage, a good while back, and heard a strange repetitive noise.
Narrowed it down to a giant cricket chomping on an old seat's leather - which have been treated with that stuff
Chewed a fair hole in it - although it wasn't exactly pristine to begin with.
Hmmm !