The other day I was watching a 3 episodes series "El Rey" - The King, the story of Juan Carlos from his early days until the COB death.

In one episode it was featured the Duke of Kent's wedding, where, according to most bios, JC and Pss Sofia became closer.

The scene in question takes place at the lobby of the hotel where several royals are staying, and Crown Pr. Constantine is telling Juan Carlos that his sister Sofia, then still infatuated with Cr.Prince Harald, locked herself in her room, crying and refusing to attend the Kent wedding, after discovering that Harald travelled to London "with his mistress".

True or fiction ?
Did Sonia travelled to London with Harald during the Kent wedding week-end ?
I don't mean that she attended the wedding, just asking if it is common knowledge that she was in London with "her lover" in those particular days.