After noticing, and alot of other people have probably noticed, the XF brake lights aren't that bright. I have come up with a little tip that will make them stand out a little bit better...
Go and find an XF wrecking, and rip out the bulb holders for the brake lights. Make sure you get the one next to the indicator, cause this accepts dual filament type lights.
Now, open up your boot and cut out your old bulb holders for the park light. This is the one next to your reverse light. If you have a bit of wiring background, you should be able to see where im going.
Now tap into the brake line on the brake light(next to the indicator) and bring that over to the new bulb holder. Also wire up the park light to the new holder.
Get a new globe(If you werent smart enough to get it with the holder!!) And plug it in.
Finally, get someone to put there foot on the brake pedal to see if the lights come on next to the reverse lights.
I'd love to post some pictures up, but I don't have a digi cam(still living in the past!!)