pld118 wrote:

They've done it now (or so they say) at the main dealer under warranty.

I'm curious whether there could be any correlation between changing the rear diff oil and a subsequent leaking pinion seal on the rear diff. The same main dealer replaced the front and rear diff oil last year. It doesn't matter anyway as its been sorted, just curious and I guess the answer would be "unlikely".

Quick clarification in the US the 2015 Supercharged FF only got active rear locking diff when Optional Rover Tow Pack was ordered. May be important in the diff seal and bearing replacement discussion.
Secondly I would support the theory that diff oil change and overfill caused the pinion seal failure as the diff oil change is actually quite complex in order to get the quantity correct. Not like the good old days where you filled it till it leaked out the fill plug hole.