Not as certain about that one Reg ?
MB have AMG as in house and Brabus as tied and loved.
Jaguar/LR seem to have the SVR badge coming up as in house and are focusing on this quite heavily. I have heard from one company I know that they are trying to focus on this as a premium/profit tool and drive up market. The new RR Coupe just released show how they think the £100k-£200k market is ripe now. They are trying to distance themselves from the KAHN and other bling masters. I think the thunder will step on their toes a bit?
I would say this is speculation so I am happy to be corrected. They are canny people at JLR these days and in ten years time it will make a good business book. Comeback from burning embers to soaring profit! Good for them. (Now give me a cheap deal on a RR!)