The third election to Rhondda Cynon Taf County Borough Council was held in June 2004.
Labour regained control of the authority from Plaid Cymru.
Roberts had been elected as a Plaid Cymru candidate but subsequently joined the Liberal Democrats.
The sitting Plaid Cymru member had been returned unopposed in 1999.
The retiring member had defected from Plaid Cymru to the Liberal Democrats since 1999.