Isle of Anglesey County Council Llaneilian (Llaneilian/Rhosybol), Llanfaethlu (Llanfachraeth/Llanfaethlu/Llanrhuddlad ward* of Cylch-y-Garn), Llanfair-yn-Neubwll (Bodedern/Llanfair-yn-Neubwll), Llanfihangel Ysgeifiog (Llanfihangel Ysgeifiog/Penmynydd), Llangoed (Llangoed and Penmon), Llanidan (Llanddaniel Fab/Llanidan), Llannerch-y-medd (Llannerch-y-medd/Tref Alaw), London Road (London Road ward* of Holyhead town), Maeshyfryd (Maeshyfryd ward* of Holyhead town), Mechell (Mechell/Llanfairynghornwy ward* of Cylch-y-Garn), Morawelon (Morawelon ward* of Holyhead), Moelfre (Moelfre), Parc a'r Mynydd (Parc a'r Mynydd ward* of Holyhead town), Pentraeth (Llanddona/Pentraeth), Porthyfelin (Porthyfelin ward* of Holyhead town), Rhosneigr (Rhosneigr ward* of Llanfaelog), Rhosyr (Rhosyr), Trearddur (Rhoscolyn/Trearddur), Tudur (Tudur ward* of Llangefni Town), Tysilio (Tysilio ward* of Menai Bridge) and Valley (Valley). <nowiki>*</nowiki> A review of electoral arrangements on Anglesey by
Port of Holyhead trade war with the newly established Republic of Ireland had an adverse effect on the level of use of the port, which caused widespread unemployment in the town of Holyhead. During the Second World War, however, the Royal Dutch Navy began using the port as a base. In June 1939, the Royal Navy submarine "HMS Thetis" sank during sea trials in Liverpool Bay and it was subsequently brought to the harbour at Holyhead after being beached at Traeth Bychan. It remained at Holyhead in dry dock while the contents were removed; fourteen of the 99 victims were buried locally. A