HC Deb 23 July 1947 vol 440 c144W
73. Mr. Stokes

asked the Parliamentary Secretary to the Admiralty whether he will define the term, "High Sea Mark," as applied by the Royal Navy to the shores of Great Britain.

Mr. Dugdale

The term "High Sea Mark" is not one applied by the Royal Navy to the shores of Great Britain. On Admiralty charts of the seas round the British Islands, the "high water line" or "coast line" is the line or mark reached by the sea when the tide rises to the level of mean high water springs.