Actor Tony O'Callaghan, who played Sergeant Matthew Boyden in 'The Bill', is set to join the cast of 'Fair City'. The actor is set to play a character called Fr Thaddeus, a priest who becomes a close friend of Dolores Molloy. O'Callaghan has also previously starred in 'The Magnificent Evans', 'Family Affairs', 'Holby City', and 'Doctors'. Advertisement The actor, who will be joining 'Fair City' before the end of the year, is also set to guest-star in 'Shameless' later this year.