Years ago, when i was still living in South Wales, i regularly walked a public right of way, through farming land towards friends of mine, who lived near Caerphilly.
One farmer in particular, was very confrontational and openly hostile towards people walking over his land.
I have often recounted my recollections with my friend, who knew the farmer i was talking about, and agreed that he was very set in his ways, and could be very aggressive towards members of the public.
He never involved the police or authorities, but i was always very cautious and on the lookout for him.
When your young and probably more afraid of those in authority, or who show open hostility towards you, its very unnerving.
It sounds very likely that the group of farmers who have involved the police, are just using their power and authority as land owners, to intimidate walkers using their land.
I suppose walking in the dead of night, might give them more concern, seeing a lone walker with a head torch.
My advice is to walk during the daylight hours, and if you are walking a public right of way, no amount of hostility can stop you walking on their property.
Its clear that they are using the presence of the Police to intimidate you.
No police officer, is going to bother to knock on anyones door, unless they have been told information that they feel needs investigation.
If you know that you have done nothing wrong, other than walk where these farmers do not want you to be, then continue walking.
It may be that a total fabrication of the truth has been given to the Police.
Theres intimidation by landowner, who shout, allow their aggressive dogs to get a bit too close, and show their displeasure at ramblers, and then there's people who fabricate a lot of false information, and inform the Police that a particular person was up to no good on their land.
Either way, you cannot confront these farmers, that's like a red rag to a bull.
Surely there must be other areas where you can go walking, because always being frightened of encountering certain hostile farmers is always unpleasant, and maybe unnecessary as well.
Such people are usually very set in their ways, and go so far, without actually using physical violence, and they can continue this way for many years, knowing that's enough to deter most ramblers or walkers.
Its when they over step the mark, and physically attack or willfully cause injury to walkers, that's when it can get very nasty.
Thankfully those instances are rare, but farming is a hard way of life, and it often needs a hard person to endure such a lifestyle, and with such hard physical labour required to run a farm successfully, comes a hard physical temperament.
Most farmers are well natured, but i am sure most of us here, have prior experience with a farmer or landowner who simply does not like walkers crossing his land.
For the average person, enjoying a walk in the country, it will hopefully be their only encounter with such people, they can shrug it off, and get over the unpleasantness, and think nothing of it when they get home.
The best solution, is not to go anywhere near their land, even if you have the legal right to do so.
If you can avoid their anger, and crossing their land, that's the best option.
Any wise person dislikes confrontation, if its at all possible, walk somewhere else.