This was particularly true of Merthyr where the electorate was increased tenfold to 14,577 .
Conversely , the borough electorate , in Cardiff , Swansea and Merthyr Tydfil had been greatly expanded .
This was particularly true of Merthyr Tydfil where the electorate was increased tenfold to 14,577 .
Conversely , the borough electorate , in Cardiff , Swansea and Merthyr Tydfil had been greatly expanded .