So, knowing full well neither previous owner or BMW dealership won't have bothered much with the leather, thought I would. When I got it used a bit of Meguiar's Leather Cleaner which worked well. I've just done passenger seat with a bit of Connolly Hide Care Cream Leather Preserver & Restorer. Says use sparingly and I have gone a bit OTT with it. Looks better, the real test will be drivers side bolster.
The original leather is more shiny. This is going matt. I may do meguiar's over the top to go shiny. Will update with pics as and when.