A Palace insider has spoken for the first time since King Charles and other members of the Royal Family, including the Princess of Wales, were heckled during a public event over Andrew Mountbatten-Windsor this week. The King led the royals and the nation in celebrating Commonwealth Day at Westminster Abbey on Monday, in what was the first big united appearance of them all together following Andrew’s humiliating arrest last month.

Andrew was arrested on suspicion of misconduct in public office but was released 11 hours later under investigation. It came after documents within the bombshell Jeffrey Epstein files showed that he may have shared confidential information with the convicted paedophile during his time as a UK trade envoy. Andrew has always denied any wrongdoing.

However, despite swiftly distancing themselves from the former Duke of York, the royals have been repeatedly confronted by protesters and other members of the public about the scandal.

The latest instance came on Monday when dozens of campaigners from anti-monarchy group Republic held huge yellow placards that read “Abolish the monarchy”, “Not my King” and “Down with the crown”.

The group’s CEO, Graham Smith, led the chant: “Charlie, Charlie, time to go.” Another sign read “What did you know?”.

Some protesters held signs featuring images of Andrew released in the Epstein files, each photo captioned: “Charles, what did you know?”

But the Abbey bells and performances from Commonwealth musicians all but drowned out the chants of the protestors, who started to yell “what did you know?” as the royals pulled up outside the entrance.

Now a Palace insider has spoken about the heckling for the first time, telling People magazine: “Other events have rocked the monarchy, but something from within — where someone is being arrested — is very different.

“This is much more serious.”

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They said Andrew’s arrest last month is “the ultimate humiliation”.

Meanwhile, author Robert Jobson told the outlet: “If it comes out that people knew stuff — whether it be members of the family or police or staffers — then heads must roll.”

The King released a bombshell statement following Andrew’s arrest, parts of which said: “"I have learned with the deepest concern the news about Andrew Mountbatten-Windsor and suspicion of misconduct in public office…

“Let me state clearly: The law must take its course.”