This is effectively set 25 years after the events of the Richard Donner film The Omen (1976) (and ignores the events of the subsequent sequels).
A talented English actor and a hobby soccer player Bradley James has previously portrayed prince/king Arthur on BBC TV series Merlin (2008-2012).For the part of Damien he had to dye his natural blond hair and become a brunette to match the original Damien.