[2] Beginning his television career as a floor manager with BBC Wales,[2] he later directed BBC television drama programmes including Softly, Softly, Doomwatch,[3] The Onedin Line, Sutherland's Law, Survivors, Angels, Blake's 7,[3] Doctor Who,[3] Juliet Bravo, Tenko[3] and Howards' Way.
[3] Regarding Roberts' contribution to Doctor Who, for which he directed five televised serials between 1977 and 1985 (starring Tom Baker, Peter Davison and Colin Baker), as well as another, Shada, which wasn't originally completed, Patrick Mulkern of Radio Times wrote, "Pennant Roberts wasn’t one of Who's most dynamic directors, but he was shrewd at casting.
He'd assign more roles to women than sci-fi scripts usually demanded and give many young actors a break.
"[4] He was also responsible for the casting of Louise Jameson as the companion Leela, having previously interviewed her for a role on Survivors.
[2] Roberts was active within the Directors' and Producers' Rights Society and chair of the body for many years.