This cache will take you on a walk just shy of two miles around some parts of Brentford that you probably haven't been to before. I would recommend avoiding it when the Bees are playing at home. Remember that X really does mark the spot sometimes.
You will need to make a note of the value for this letter, which can be found on the log, in order to find some bonus caches.
The container has a log sheet but no pen.
If you feel inclined, then feel free to write your log with an alphabet theme - ? is also for.... or in any other alphabetic sense that inspires you.