Part IV
| Bridgend (county constituency) | The following wards of the Borough of Ogwr, namely, Brackla, Cefn Cribwr, Coity Higher, Cornelly, Coychurch Lower, Laleston, Morfa, Newcastle, Newcastle Higher, Oldcastle, Porthcawl East, Porthcawl West, Pyle and St. Bride’s Major. |
| Caerphilly (county constituency) | The following wards of the District of Rhymney Valley, namely, Aberbargoed, Aber Valley, Bargoed, Bedwas and Trethomas, Gilfach, Hengoed, Llanbradach, Machen, Maesycwmmer, Morgan Jones, Nelson, Penyrheol, St. Cattwg, St. James, St. Martins and Ystrad Mynach. |
| Merthyr Tydfil and Rhymney (county constituency) | (i) The Borough of Merthyr Tydfil; and (ii) the following wards of the District of Rhymney Valley, namely, Abertysswg, Darren Valley, Moriah, New Tredegar, Pontlottyn, Tir Phil and Twyn Carno. |
| Ogmore (county constituency) | (i) The following wards of the Borough of Ogwr, namely, Bettws, Blackmill, Blaengarw, Caerau, Llangeinor, Llangynwyd, Maesteg East, Maesteg West, Nantyflyllon, Nant-y-Moel, Ogmore Vale, Pencoed, Pontycymmer, St. Bride’s Minor and Ynysawdre; and (ii) the following wards of the Borough of Taff-Ely, namely, Brynna, Gilfach Goch, Llanharan and Llanharry. |
| Pontypridd (county constituency) | The following wards of the Borough of Taff-Ely, namely, Beddau, Church Village, Cilfynydd, Creigiau, Glyncoch, Graig, Hawthorn, Ilan, Llantrisant Town, Llantwit Fardre, Pentyrch, Pont-y-Clun, Pontypridd Town, Rhondda, Rhydfelen Central, Rhydfelen Lower, Taffs Well, Talbot Green, Ton-teg, Tonyrefail East, Tonyrefail West, Trallwng, Treforest and Tyn-y-nant. |
| Rhondda (county constituency) | The Borough of Rhondda. |