I actually haven't, but I read the book years ago.
The book itself was a very much 'written as fiction so I don't get sued' as it's basically about Harold Wilson's government with a bit of the CIA's removal of the Australian PM sprinkled in. Sir Peregrine is based upon Peregrine Worsthorne, the fascist deep state journalist / broadsheet editor who said (amongst other things) that treason was acceptable so long as it was to reaffirm American interests in Britain.
I believe the author added a section after the coordinated Corbyn coup / smear campaign too, but my copy is from the 80s so I haven't read it that bit.
I might have to give this a watch though if it's just sat on YouTube. Cheers.