Millie i don't know the reason why his legs are going brown but he sounds delightful. Please can you add a photo to your question? For most shrubs a geberal fertilize such as Growmore, vitax, ioracle grow etc can be used if necessary.

Thank you for advice ha ha ha haven't worked out how to upload photo as yet did a long time ago but now cannot remember how I did it sorry .

You can add one to your photo page easily though.
Having thought about this a bit more, and guessing its made of box, the very bottom will tend to go bare won't it - don't know how you can prevent it. But you can always say he has brown trotters...
Or grow something low growing underneath that will conceal his feet.