Do Genuine Rubber mats from say a 2003 fit a 2012/2013 ??

No they don't, well not exactly.
I took the rubber mats from my old MY05 TD6 when I got a MY12 Westminster TDV8, the front mats fit okay, but the rear mats won't fit. Think there's a minor change in the floor layout in the rear that stops them fitting.

Ah great thanks for that , I thought there maybe a slight difference

The older BMW seats had different mounts to the newer Ford/Jag seats

https://www.fullfatrr.com/forum/topic22710.html

The mats from my 2004 322 fitted into my 2012 322. There is a slight difference in the rear footwell, but I deemed the fit adequate. The best thing is probably to take your existing mats to an example of the newer car and see what you think. Only Range Rovers since 1988

Facelift cars have locating hooks in the front carpet, too - the early mats don’t have the holes for them.

Agreed. I put the rubber mats on top of the carpet ones. It's not recommended by LR, presumably due to fear that the driver footwell mat will bunch up under the pedals, but that never happened to me. Only Range Rovers since 1988