Sorry if this is in the wrong place, but, our new neighbours have bought the field at the bottom of my garden, do they need to change use?

[Swifey]

It is agricultural land, usually used for calves, or sheep, the occasional bull, and a few times for grazing a few ponies for a couple of weeks at a time. That is all fine, and expected. Unfortunately new people have moved in next door (detached) and have now put down hard standing in the field, have vans and a motor home parked down there, and have a large field shelter too. It is now very much equestrian and whilst that doesn't bother us too much, all the vans etc, and the hard standing does. It totally seems that they have changed the 'use' of that land?
They are also running a ground works business from the house - jcb's and vans and lorries all the time.
Has anyone got any advice please?

Ring the council and ask them.

they might need planning permission for the hard standing , have a look at your council's planning portal.

Is there any chance of your garden flooding due to their hard standing? (not allowing water to drain into the grass iyswim)

Is the land level or lower or higher than your garden?

It's level, but the other side of a small stream, that has flooded once in the last 10 years.

They will ned planning for the hard standing and any fixed stables. They will also need change of use from agricultural to equine - horses can be used to graze the land but that must be proven to be their sole source of food and having stables and a hard standing negates this. Contact the planning. If they have done it without planning they may also find themselves hit for business rates - equestrian properties are all liable (you can apply for a reduction once you have proved you don't make an income) but the council usually let it slide as they have no idea who has what usually. If they make themselves known as breaking planning regulations the council may choos this opportunity to enforce it.