High Quality Content by WIKIPEDIA articles! Joseph Charles Mortimer Byrne is a fictional character from the BBC medical drama Holby City, portrayed by Luke Roberts. Joseph first appeared in the 3 January 2006 episode "Mother Love", series eight, episode twelve of the programme. Roberts had made an unrelated guest appearance in the previous series of the show, playing the relative of a deceased patient, and was asked to return in a more permanent role by the series producers.