I have done a little research and one new brewery in Wales is:

Bragdy Ynys Môn
Cae Cwta Mawr
Talwrn
Ynys Môns
LL77 7SD
Phone 01248 723801

I did try a pint of one of thier brews last week but I can't really offer an opinion as I had drunk a few pints of Guinness before trying it.

I used to love Pedwar Bawd/ Four Thumbs bitter that was brewed by Bragdyr Dyffryn Clwyd in Denbigh. I have just found out that they were taken over by:

Flannery's Brewery Ltd
Tyn Parc Farm
Llandre
Bow Street
Aberystwyth
SY24 5BU
Phone 01970 820332

Jon