by Malcolm Prior
Inside Out, BBC South
Campaigners claim a 17th Century law could give them the right to row along one of the South's protected rivers.
Canoeists cannot access large stretches of the River Avon
Canoeists say landowners are barring them from stretches of the Avon in Wiltshire, Hampshire and Dorset.
But now a university researcher has uncovered a 1664 statute that he claims gives people the right to get on the river wherever they want.
Landowners are adamant there is more than enough access and are consulting legal experts about the claim.
The row over the river, which is a site of special scientific interest, has been brought to light by BBC South's Inside Out programme.
River access researcher the Reverend Douglas Caffyn told the programme he believed the "Act for making the River Avon navigable from Christchurch to the city of New Sarum", made under Charles II, was still relevant today.
The Law Society has confirmed that the act has never been repealed.
The Rev Caffyn said: "My view is that the earth was created by the lord and everyone should have the right to appreciate the beauty of the countryside.
"People should not be allowed to purchase a piece of land and exclude the general public all of the time. I think that is wrong."
He has written to landowners along the Avon explaining why he thinks people have a legal right to access the river.
The Rev Caffyn says the 1664 act gives public navigation rights
"No-one has written back to me explaining to me why they think those reasons are invalid. I don't think they can," he said.
"Some things in life are fairly certain and the fact that there is a right of navigation on the Avon is one of them."
However, with the claim yet to be tested in court, landowners remain sceptical about its validity.
One landowner, Rae Borras, who owns a mile-long beat on the Avon, said of the Rev Caffyn's argument: "Anything can be argued - that's really what English law is about, precedent etcetera.
Canoeists have to negotiate access with private landowners
"It could well be that Edward II gave somebody a mining right somewhere in a village where now there are gardens but I wouldn't expect people to just remove their flowers and get on with mining."
Mr Borras argued that there was plenty of access for canoeists at the tidal mouths of the Avon and other nearby rivers.
He said: "There's Poole harbour, Chichester, Christchurch harbour - these are areas that are easily navigable. Why do they have to add to that which they can already use by coming up to here?"
Currently there is no blanket legislation giving people the right to navigate rivers in England and Wales in the way ramblers were given the right to roam the countryside.
Inside Out will air on BBC1 in the South at 7.30pm on Friday