Sch 6 para 13 Crown foreshore
(1) Where— (a) a person is in adverse possession of an estate in land, (b) the estate belongs to Her Majesty in right of the Crown or the Duchy of Lancaster or to the Duchy of Cornwall, and (c) the land consists of foreshore, paragraph 1(1) is to have effect as if the reference to ten years were to sixty years. (2) For the purposes of sub-paragraph (1), land is to be treated as foreshore if it has been foreshore at any time in the previous ten years. (3) In this paragraph, “ foreshore ” means the shore and bed of the sea and of any tidal water, below the line of the medium high tide between the spring and neap tides.