Following her shock departure from the group in 1998, Geri - who was also known as Ginger Spice - performed Happy Birthday To You to the then-heir to the throne at his 50th birthday party.
The insider went on to explain that there is a “sense” that the reunion could happen for an event this “significant” - which has not taken place in Britain since the coronation of Queen Elizabeth in 1953 - and claimed that group members Melanie C and Mel B are the ones “trying to make it happen”.
The claims come just days after I Want You Back hitmaker Mel teased that a new project was on the horizon for the band - who last reunited for a stadium tour in 2019 without Victoria - but was unable to say exactly what it was.
She said: “I can’t tell you exactly, but there’s going to be something that is going to be announced pretty soon. I am probably going to get told off. It is a project that we’re very excited about. It will be all five of us.”