I recently came across this product: https://www.obenaufs.com/obenaufs-oil-s/112.htm lt got mostly excellent reviews & after a couple of coats of the oil on the new drivers seat for Bruiser, l think l can see why. The leather has really softened up very quickly indeed. I gave my new workboots a going over too which is what the product was originally formulated for. lt can darken the original colour a little but Bruisers seats are black anyway, though l have other seats l'll use it on. It's quite cheap in the U.S. but they don't ship to the U.K. & outlets for it seem pretty limited. In the end l got the 16oz oil, 8oz LP balm & the 16oz cleaner from Amazon, much as l dislike lining their immense coffers, for £81 inclusive. Pricey but it seems like it will go a long way & it's a lot cheaper than re-upholstering an interior.