Source Merlin

Treasury civil servants and/or George Osborne are clearly keen on le Carré. From a summary of "Tinker, Tailor, Soldier, Spy" comes "'Witchcraft' is the codename for the information obtained from source Merlin, supposedly comprised of a high-ranking Soviet [defector], and a number of other, advantageously-placed disloyal Soviets. The information is very profitable, and waters the mouths of informed Englishmen and Americans alike." Should one substitute "banker" for "Soviet" and apply it to the recent agreement?