Caerphilly () was a constituency of the Senedd. It elected one Member of the Senedd by the first past the post method of election. It was additionally one of eight constituencies in the South Wales East electoral region, which elected four additional members, in addition to eight constituency members, to produce a degree of proportional representation for the region as a whole.
Boundaries
The constituency was created for the first election to the Assembly, in 1999, with the name and boundaries of the Caerphilly Westminster constituency prior to the 2023 review of Westminster constituencies.
The other seven constituencies of the South Wales East electoral region were Blaenau Gwent, Islwyn, Merthyr Tydfil and Rhymney, Monmouth, Newport East, Newport West and Torfaen.
Voting In general elections for the Senedd, each voter had two votes. The first vote was used to vote for a candidate to become the Member of the Senedd for the voter's constituency, elected by the first past the post system. The second vote was used to vote for a regional closed party list of candidates. Additional member seats were allocated from the lists by the d'Hondt method, with constituency results being taken into account in the allocation.
Assembly members and Members of the Senedd ElectionMemberParty 1999 Ron Davies Labour 2003 Jeffrey Cuthbert 2016 Hefin David 2025 by-election Lindsay Whittle Plaid Cymru
Results
Elections in the 2020s A by-election was held on Thursday 23 October 2025, following the death of Hefin David in August 2025.
Regional Ballot void votes: 145. Want of an Official Mark (0), Voting for more than ONE party or individual candidate (71), Writing or mark by which the Voter could be identified (4), Unmarked or Void for uncertainty (145)
Elections in the 2010s
Regional ballots rejected at the count: 143
Elections in the 2000s
2003 Electorate: 68,152 Regional ballots rejected: 316
Elections in the 1990s
References