MARS OIL, (Mars Care Proofer), would be my recommendation. My dad served his time making and repairing leather goods, mostly shoes, in the 1930's and Mars was the treatment of choice. My brother and I brushed it on the TT and Lewis leathers and when on "unplanned excursions" on the track they slid well with a wonderful smell. Also used on the leather car seats and walking boots. Still have half a gallon left over from the '70's, it goes a long way, still available today although no longer fish oil based. There is a similar product called Carrs Leather Oil but have no experience of this. Mind you if its peeing doon get a cheap one piece nylon oversuit as sodden leather weighs a ton and must be dried very, very slowly to preserve the texture.
