Complex sentence: Rhys was best known in local government as chairman of the Aberdare Local Board of Health from the 1860s until its abolition, when he became an inaugural member and first chairman of the Aberdare Urban District Council.
Split into simpler sentences: Rhys was best known in local government as chairman of the Aberdare Local Board of Health from the 1860s until its abolition. He then became an inaugural member and first chairman of the Aberdare Urban District Council.