Two points, 1) it could have gone through an enigma machine, but that should have been broken by now. 2)it could be a personal variation on a well known code, upping the difficulty, but really?
PS +The Wall Street Journal
GCHQ is not the UK's intelligence service, its one of the UK's intelligence services, specifically the one that handles SIGINT and governmental communications security, just like the NSA does for the US. Factcheck Fail!