The legal position concerning planning and boundaries is complicated and litigation can go on for years. As already stated, common courtesy should have been applied, and the neighbour should have discussed his plans with you. As far as ownership of the fences is concerned, I think you will find that the owner of the property on who's land the fence posts are is responsible for the maintenance of the fence, and this implies ownership. But again, the (UK) law is vague and counter-claims can go on for years. Each case, as it is civil and not criminal law is weighed on its merits and there is no 'guilty' or 'innocent' as such. It will be judged on a balance of probabilities. And as for maintenance (rendering) of the brick wall, it belongs to your neighbour and is his responsibility. You have no liability for maintenance.I understand that UK law is vague on this point, too and basically says that to maintain the wall, the owner must get permission to come onto your property to conduct maintenance, but also has right of access to maintain his property!! Get out of that one!