Parliamentary supremacy which ultimately derives from the Crown is misleading in this context since the sovereignty rests in Cornwall with the Duchy rather than the Crown Since the original Duchy charters are difficult to get hold of light may be shed on the case by considering the Cornish Foreshore Case of the 19th century whereby the Duchy whatever it may publicly say today again you are confusing the Duchy estate land holdings with the territorial Duchy itself argued that it was sovereign in Cornwall and hence had the right to the foreshore The other thing is that since the concept of Cornwall is broader than the present administrative unitary authority since 2009 and the previous County Council administration 1889 2009 to assert Cornwall was established by the 1888 Act of Parliament is simply plain wrong