The name given to the provisions of the Acts of Union 1536-1543 by which the English system of dividing the country into shires or counties for the purposes of local government, the administration of justice and parliamentary representation was applied in Wales.
The Statute of Rhuddlan had partially applied this system to the former kingdom of Gwynedd (which was divided into Anglesey, Caernarfon, and Merioneth), and something akin to the English notion of a county had developed in the royal territories of Cardigan, Carmarthern and Flint. In addition the the marcher lordships of Pembroke and Glamorgan had developed into something like feudal proto-counties.
This process was now completed and extended to the rest of Wales, establishing a comprehensive system of counties; what might be termed the historic counties of Wales that survived until 1974 (in a political sense) and still have relevance today. If only because the county boundaries where nor arbitary but based firmly on the old Welsh divisions of cantref and commote.
As a result it effectively established the territorial boundaries of Wales although this was not the intention. As Wales and England were to be effectively united into a single legal jurisdiction, the boundary between the two did not matter. The method by which land was divided up between 'Welsh' and 'English' counties was purely administrative convenience; many former marcher lordships such as Oswestry and Ewyas were simply parcelled off into Shropshire and Herefordshire, and were therefore 'lost' from Wales.
The newly created counties created the basis for the formation of the circuits of the court system known as the Courts of Great Sessions, with
twelve counties now grouped into four judicial circuits and the thirteenth, Monmouthshire, being linked with the Oxford circuit. (Which of course gave rise to the misguided notion, much prevalent in later centuries, that Monmouthshire was not part of 'Wales'.)
Along with this division into counties for the purposes of local government and the administration of justice came the provision of representation for Wales in parliament. One member of parliament was allocated for each county and one for each county borough, except that Merionethshire was not considered to have any town worthy of borough status and so Monmouthsire was given two county members. In 1543 Haverfordwest was made a parliamentary borough
and hence Wales sent a total of thirty seven members of parliament.
The basis for the formation of the thirteen shire counties of Wales.
The counties of the principality of North Wales, that is
remainded unchanged except that
Merionethshire now included the former marcher lordship of
Mawddwy
In the other royal counties, that is
Cardiganshire remained unchanged but
Carmarthernshire was expanded to include lands on the eastern bank of the river
Towy namely
Cydwelli,
Is Cennen and
Llandovery, and
Flintshire now included the
marcher lordships of
Ystrad Alun and
Hawarden.
For the remainder of
Wales shires were formed from the following
marcher lordships;
- Breconshire from Brecon Builth and Blaenllyfni
- Denbighshire from Denbigh, Rhuthin Bromfield and Yale and Chirk
- Glamorganshire from Glamorgan and Gower
- Monmouthshire from Gwynllwg, Abergavenny, Monmouth, Usk, Caerleon and Chepstow
- Montgomeryshire from Powys, Cedewain and Ceri
- Pembrokeshire from Pembroke together with Pebidiog, Cemais, Cilgerran, Llawhaden, Wiston, Haverfordwest, Narnerth, St Clares, and Laugharne
- Radnorshire from Gwrthernion, Elfael, Radnor and Maelienydd
SOURCE A History of Wales by John Davies