wingrovebuyer : Hello. I would put a sign at either end, saying walkers should keep to the defined path and dogs must be kept on leads. You could also say "Anyone deviating from the legal footpath will be considered a trespasser" or words to that effect. It is very important to prevent people using the bigger field, as they may establish new rights over it. These signs will help prevent that. You could also put a fence along the edge of the path, separating off the rest of the field, but that may be costly.
wingrovebuyer : Appreciating that you don't want to offend anyone, the notices do need to be robust enough to prevent any confusion as to what walkers can and can't do.
wingrovebuyer : Wording to the effect that dogs must be kept on leads is not legally enforceable but gives users the right idea. You could also say "Dogs must be kept under control" which is perhaps more friendly.
If people persist to let dogs and themselves onto the field what recourse do I have
wingrovebuyer : It's problematic, because you'd have to catch the in the act either personally or on CCTV etc.
wingrovebuyer : However, your recourse would be to warn people off, saying if they trespass again you will have no choice but to take legal proceedings against them.
wingrovebuyer : These would be civil proceedings, in which you would ask for an injunction to prevent further trespasses. It's all a bit sledge hammer and nut, but it is the only way to prevent further incursions. Anyone ignoring the injunction would then be open to criminal prosecution.
wingrovebuyer : Is fencing the path off out of the question?