Oh dear me! Thanks everyone for your really helpful suggestions. However, I've no studs, zips, buckles, back-pocket combs or whatever to account for it; and I've applied hide food several times in the 4 months since I took over the Roadster.
Think I'll get it outside in good light tomorrow and have a really good look: I'm starting to wonder if it's dye from my jeans that's rubbed off on the bolster, and looks as though the leather facing is wearing off
I'll report back - and be prepared to eat humble pie!
