<porth> 'cove, enterance' + <trega> '?enclosed farmstead' + <Urien> personal name
Historic forms:
Tregorrian Cove 1699
Watergate Bay 1813
Watergate Bay 1826
Watergate Bay 1830
Watergate Bay – 1st Series OS
Watergate Bay – Current OS
Tregurrian or Watergate Beach – Current OS