Huggybear in regards to Beaches, if it is privately owned beach which some are in my place of birth Devon then permission has to be sought end of. Now as to how far from the beach is still classed as owned, then we have to go back to very old yet active law (1980's it was still active). This relates to salvage rights. Best way to explain it would be an old story involving one of my relatives who was a salvage operator off the coast of Devon. He for many years had been looking for a very old wreck with a lot of 'Spanish gold' on it. He believed it was off the coast very near to shore in Devon. After many years searching this particular area and lots of research and three days after a major storm he found it. He started to vacuum a hell of a lot of 'Spanish gold coins' and informed the authorities. Now unfortunately for him the land and beaches in shore were owned by the National Trust and these wise guys, used a very old law that states 'A standard barrel of brandy is to be floated out to sea, as far as man can see the barrel becomes and is the property of shore (beach) owner (just a gist of what legally was stated).' National Trust were not attempting to claim 50/50, at the time they were attempting to claim the lot. So if the court accepted this antiquated law then one can assume an owner of a beach owns the lot no matter how far you go out (low or high tide).
Now Councils work or are supposed to work in the public interest. UK.Gov encourage Councils to sell off land which is classed as surplus to requirement with the intention of assisting the building of modern housing. Basically a Council is entrusted by its voted in Councillors to make the best use of the public purse. Sometimes keeping land and maintaining that land can cost the public a lot of money, and therefore it is deemed wiser for the public to sell off the land and create financial revenue that can be used in a better way. At times it may be used to buy more land in a more productive area.