The KGB codename rumored for Harold Wilson in season 3 of The Crown is Olding.
“Olding” is the title of season 3’s opening episode, which introduces Wilson as Britain’s new Labour prime minister amid suspicions that he might secretly be working for the Soviet Union. The episode presents the allegation as a rumor and political anxiety, not as an established fact about Wilson.
The storyline draws on real Cold War-era suspicions. British intelligence maintained a file on Wilson, and his contacts in Eastern Europe helped fuel conspiracy theories. However, the series dramatizes and compresses those concerns for television. Wilson was never proven to have been a KGB agent, and the show ultimately shifts attention toward the real Soviet spy operating near the royal household: art historian Anthony Blunt.
“Olding” is easy to confuse with “Cambridge,” which refers to the Cambridge Spy Ring, or “Beryl,” a different codename from the series’ espionage plot. The answer is specifically the alias attached to the rumor about Wilson in the season’s first episode.