Post Office – Haverfordwest, Trevine – Opening Hours & Branch Details Post Office is found at 37 Ffordd Y Felin, 12.69 miles north-west of the centre of Haverfordwest (close to Trefin Square). The branch is a significant addition to the locales of Trevine, Mesur-Y-Dorth, Llanrhian, Square And Compass, Abercastle, Croes-Goch, Porthgain and Trefin. Regrettably, it’ll be closed for all of today (Friday). Read the information on this page for Post Office Haverfordwest, Trevine, including the hours of business, place of business address details, telephone details and more.