I need to replace the bulb in my rear deck brake light: 2005 XKR Coupe. Is the bulb accessed from the trunk or inside of the car at the rear deck light housing? If someone has the bulb number handy that would also be helpful.

Thanks in advance for the help.

 

If you are meaning the 3rd brake light in the rear window, it isn't a bulb, it is a LED bar.

You can do something like this:
https://www.jaguarforums.com/forum/xk8-xkr-17/$13-99-third-brake-light-repair-27177/

It s also possible to replace all the individual components on the stock circuit board. Cheap to do, if you are handy with a soldering iron.