Granted, they would have had barely any influence or power, but Welsh, Manx, Irish and Scots Gaelic speakers would have numbered more than 1% in 1936.
Oh, and Plaid Cymru was a politically active party in Wales by 1944 with a fair bit of support in the North and Powys.
And Mumia, you're wrong about the naming system- in the 1960s all the Welsh counties were renamed officially into the Welsh language. For example, Monmouthshire became Gwent etc
No, there was never any official renaming of Cornish, Scottish, or Welsh towns or cities like there was in Ireland, such as the British did before the Irish Free State in the 1920s. South Wales and the Welsh Marches (Central Welsh Borderlands) use both English and Welsh names (i.e Casnewydd: Newport, Caerdydd: Cardiff) but North and Central Wales are Welsh speaking enough to even make the English use their own, local names

.
I'd suggest Wales should be three provinces. Cardiff, Aberystwyth, and Swansea.
Cardiff would be the most VP and IC, Aberystwyth would be North Wales, and Swansea would, like Cardiff, also include a large amount of raw materials so as to represent the amount of coal mining and heavy industry there at the time.
Go Cymru!

Hope having a Welshman on the case solves this problem!