Exactly as I understand it, Evan. If the landowner discovers you're using the land and doesn't mind, as soon as he tells you so within the stated timescale, that's it, your anticipated claim is finished.
.
The case I cited goes back to the 19th century, but was challenged in the 90s because the farmer said they were trespassing on his land and he forbade them from fishing. If he was telling me the truth, then the courts upheld his claim, but stated that the society did own the fishing rights, yet had no right to cross his land. It was a strange case.
We did have a woman by the side of one of our lakes that claimed a little extra land stating that they'd "looked after it" for the past 15 years. It was a load of cobblers, as they'd occasionally parked a few cars on it WITH the permission of the previous owner. They were, as is common today, trying it on.
If a club buys, licences or rents fishing rights then, apparently, the owner HAS to grant access across his land othewise it's an unfair contract.