The area of sea (excluding the exclusive fishery limits) contained within a line drawn from the coast of England along the southern boundary of the mouth of the River Tweed to the eastmost point of that boundary; thence due east to the intersection with the boundary of the fishery limits of the British Islands; thence along that boundary in a clockwise direction around the coast of England and Wales to the intersection with the parallel of latitude 54° 30&min; north in the Irish Sea; thence eastwards along that parallel until it meets the coast of England.