(adjective) of, forming, or resembling the Roman imperial bodyguard / (adjective) of or relating to a praetor
Burgess, Philby, Maclean, Blunt, and their praetorians
used metaphorically here I assume
With a past checkered with praetorian preeminence
The rise of New Labour had seen the unions, traditionally the praetorian guard of the Labour leadership, cast out