Yes if it's his fence. But what is to stop you re-painting it another colour?! Why not just tell him he's being rude, annoying and inconsiderate and should paint it brown?
how can he paint your side of the fence if he can by law ;then the law is an ass?one way is dont allow him on your property. if this doesent work get up at 3in the morning and paint is side bright pink with yellow dots??
Your neighbour needs your permision to paint your side of his fence.He may be responsible for upkeep of the fence but he cannot enter your property without you first agreeing to this.