As we've had a few days of nice weather, in between the rain, my MRS has been slapping on the sun lotion. Now that's good, don't want her to get burnt, but now it's on the leather interior

What's the best way to clean this off and should I treat the seat afterwards?

Any help welcome.

Not sure on the best way to remove it, probably wipe with a clean cloth and treat with leather cleaner and feed.

However, we test car interior trim parts at work and one of the worst things that you can get onto a coated surface is suntan lotion. It can lift paints and also leave stains behind. As a result I am very careful what it comes into contact with.

Try baby wipes first, failing that get some saddle soap from your local horsey place. Or you could try some Gliptone GT14 or GT12 http://www.liquidleather.com/car-shop.html