Thank you so much for your thoughts and suggestions. It is very much appreciated. I suppose our main concern is that the property owner may have an ulterior motive and that we need to protect our easement rights, however an unlocked pedestrian gate may resolve the conflict between us and the new owner and avoid it escalating, so we are a bit torn.
I suppose my main question now is, if we allow an unlocked pedestrian gate that is smaller than the size of the easement, which will be workable for most of us, most of the time, will the servient easement holder later be able to argue for a reduction in the size of the easement, and therefore be allowed to develop the block further and closer to our properties? Also, at some point in the future, we may need to use the access to the full size of the easement (to bring in equipment or vehicles to work on the woodland area at the bottom of our respective blocks), however this hasn't been required in recent years and currently the main use of this easement is for pedestrian access.
The issues you mention above, is why, a gate on an easements are normally not allowed in residential areas, as it an excessive burden to the dominant title holders, now and into the future.
Why do the servient title holders want the gate, locks and insurance? most likely to piss you off and to stop you using the land, which will have no weight in court.
Just remember, that you or the previous owner, most likely paid a fee to the servient title holder (or previous holder) to use that piece of land, and now after the fee has been spent, they want to decrease your enjoyment of the easement.
Write a letter, stating, that the proposal is an burden to your enjoyment of the easement (now and into the future etc) and reasonable force will be used to remove any gates and locks. Also get other users to right the same letter and send it to them.
if you end up cutting locks etc, and they call the police, the police will tell you/them its a civil matter and they wont do a thing as, you have a legal right to access that part of the land.
And finally, if you do let them put the gates up etc, good luck getting them removed in the future.