Bought this porcelain ginger grater in the Lakeland store for 3 quid and found it really useful for cleaning the bristles of brushes. The ‘teeth’ (bumps?) are just the right size and easy to clean. I’ve been using it a lot.
(FYI The brush beside it is a speckling brush – great for producing random spots of paint but you have to make sure it’s pointing the right way or you end up with a face full of purple freckles!)