The law is complex but, as long as the covenant 'touches and concerns' your land you can apply for a court order requiring your neighbour to abide by the provisions of the covenant:
https://www.telegraph.co.uk/finance/property/advice/propertyclinic/9257999/Property-clinic-restrictive-covenants.html
Most such covenants seem to get totally ignored though (with nobody ever doing anything about it). Every house around here has a covenant prohibiting external TV aerials but, because this is a 'fringe' area for reception, all the houses have got TV aerials on them. There are also covenants requiring that front gardens be 'laid mainly to lawn' but, due to lack of parking spaces, most of them have been paved over. There's even a covenant on my property requiring me to mow the grass on a piece of communal land has now unofficially been absorbed into another house's garden. (It's not even on the same road as my house!) I'm sure the house owner there would give me a very odd look if I turned up with a lawnmower on 'his' land!