Speculation is rife that the engagement could be announced as soon as tomorrow after bookmakers closed betting on the couple getting engaged.
On Friday the world was waiting for news of the royal engagement but it never came.
A Government source said: “Everyone was expecting the announcement to go out at 11am on Thursday.
“We think the Palace got spooked by phone calls from various media outlets. The statement was being prepared on behalf of the Prime Minister.
“It’s now being considered a case of any day now.”

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The fact that Meghan Markle is now being guarded by royal protection officers is the latest sign that an engagement is imminent.
The American actress was accompanied by bodyguards from the Metropolitan Police’s Protection Command while out and about in London on Tuesday.
Meghan flew to London on Tuesday from Canada, where until recently she has played the role of paralegal Rachel Zane in Suits.
There been reports that Meghan had moved her dogs to the UK, while removal vans have been spotted in her Toronto neighbourhood recently.
The Archbishop of Canterbury will asked to give his blessing to a church wedding for Harry and US divorcee Meghan Markle, the Daily Express understands.
Harry whisked the Los Angeles-born actress away to Botswana for her 36th birthday in August. Some say he may have proposed during the trip to Africa.
The Duchess of Cambridge became secretly engaged to Prince William in Kenya, almost a month before an official announcement was made in November 2010.
William Hill are offering 5/6 that Kensington Palace make the announcement on Prince Harry getting engaged to Ms Markle before the end of November.
Whilst it is 2/1 that the announcement is in December.
“The odds suggest that the announcement will happen before midnight on Thursday and I certainly would not bet against it,” said William Hill spokesman Rupert Adams.
Latest royal odds on when Kensington Palace will announce royal engagement: 5/6 In November, 2/1 December, 3/1 January 2018 or later.