Kensington Palace's official announcement yesterday said that Prince Harry and Meghan Markle will be getting married in "spring 2018".
However, according to Paul Burrell, a royal wedding in June is unlikely.
Speaking on ITV's Lorraine this morning, he said: "It can't be June, because the royal Ascot is in June. Granny goes to the races in June."
Burell, who is said to have been Princess Diana's close confidante, predicted that the much-awaited wedding will take place either in "late April" or "early May."
The former servant of the British Royal Household also speculated that Prince Harry's wedding will be less extravagant than that of his brother. "Small! It's going to be smaller [than Prince William and Kate Middleton]."
He went on to say that St George's Chapel, Windsor Castle is the expected venue. "It's a beautiful space, and it's not very far for Granny to come down the hill," said Burell speaking of the Queen.
The 59-year-old former footman to the Queen, said that Prince Harry would most likely have consulted Prince William about the engagement ring.
"William must have said to Harry, 'What would you like to give to Meghan? Something of Mummy's, because that's right and that's what Mummy would want.' And that's true. She would," Burell said in the interview.
He added: "That ring on her finger will always remind her of the legacy which she's married into."
Burell admitted that no one could have foreseen Prince Harry marrying Markle: "Who'd have thought an American, divorcee, Catholic would have married a Prince of the United Kingdom?"
But he also said that during the couple's first TV interview after the engagement announcement, it was clear that the two were in love. "They adore each other and it's a lovely, lovely thing to watch unfold."