The former Neighbours regular made headlines when she partied with the royal playboy in December, only to later admit she didn’t recognise him.
Now Margot has confessed she actually thought Harry was pop singer Ed Sheeran.
“Everyone now thinks if they come on a night out with me in London they’ll bump into Prince Harry,” The Wolf of Wall Street star tells The Sun.
“But I didn’t even know who it was. I’d had a drink or drinks. I thought I was hanging out with Ed Sheeran.”
Margot had been rubbing shoulders with the British royal at an event hosted by model Suki Waterhouse.
She added: “I was thinking “Ed’s a really cool guy. I’m going to take some pictures with him’.”
The resulting photo booth snap – which also featured A-list party guests Sienna Miller and Cara Delevingne – later went viral on social media.
Margot jokingly told The Sun that Harry didn’t take the mix up well, but she did not explain further.
Margot previously spoke about the incident on The Tonight Show With Jimmy Fallon in March.
She said: “When I saw him in those glasses, I was like, ‘Oh, my God, I didn’t know Ed Sheeran was at the party!’ And he got really offended.”