Post Office – Haverfordwest, Mathry mobile service – Opening Hours & Branch Details Post Office is found in a convenient location on Layby On Village Green, about 11.16 miles north-west from the centre of Haverfordwest. This branch is an excellent addition to the local businesses of Carnachenwen, Abercastle, Square And Compass, Granston, Mathry and Castle Morris. Today (Friday), you can drop by 9:00 am until 10:30 am. This page will supply you with all the information you need about Post Office Haverfordwest, Mathry mobile service, including the open hours, navigation, email address and additional details.