I remember the series from the 80s'. Low budget typical of the days but an engaging plot with 'Cromwell' type 'fundamentilists' ruling a post apocalptic Britain with , unknown to himself, a royal stirring up dissent. You half expected Charlton Heston to suddenly turn up.
This noveliastion is actually better than the series like some of those old Target Doctor Who books and gives you space to decide on the characters youself. They should remake it with CGI and Ken Brannagh reprisng his role as Heydrich in Conspiracy.