Guy Fawkes was a Roman Catholic extremist who hoped to see his version of Christianity imposed by force on the rest of the country.  He resorted to terrorism and failed.

Some people think the Pretender, who would call himself King James the Third, and his supporters, the Jacobites, had a similar agenda.  Not everyone agrees.  There is some discussion of that in Highwaypersons, when the main characters come across Jacobites and some of their sympathizers.

They find that life is not as simple as some people would make out.  Oscar Wilde said, “The truth is never pure and seldom simple”.

You might see a similarity with attitudes towards Islam today.  And similar differences within Islam.  Perhaps there is hope for a similar peaceful accommodation in the long run.  You must decide how relevant the parallels are.

However, the book is not a political treatise.  The politics and philosophy never hold up the action for long.