Aeronwy Bryn Thomas-Ellis ( 3 March 1943 -- 27 July 2009 ) was the second child of the Welsh poet Dylan Thomas . Aeronwy Bryn Thomas-Ellis ( 3 March 1943 -- 27 July 2009 ) translator of Italian poetry , was the second child and only daughter of the Welsh poet Dylan Thomas and his wife , Caitlin Macnamara .