Complex sentence: Prior to being elected as Member of Parliament for Sefton Central, he was the Labour Councillor for River Ward in Medway, a unitary authority in Kent, a ward that he had represented since the creation of Medway Council.
Split into simpler sentences: Prior to being elected as Member of Parliament for Sefton Central, he was the Labour Councillor for River Ward in Medway, a unitary authority in Kent. A ward that he had represented since the creation of Medway Council.