I had an elderly friend Jack Lilley whom I sold a Freeman 22 and he would tell me how he hated these signs on the Crown Estate stretch of the river.
Jack you see was a WWW2 veteran, a motorcycle dispatch rider who was evacuated from Dunkirk. After the war he started a motorcycle business which is still going to this day. It was his firm belief that he should be able to moor where he liked on the perfect for mooring banks of the Crown Estate land " I fought for that land I can moor there" he would tell me. I agree with him.