Prince Harry and Prince Andrew's 'Spare' parallels resurface after extraordinary breach of royal protocol - analysis by Cameron Walker

Most conversations have remained private, but Sir Mike has chosen to reveal what the monarch thought about potentially sending her grandsons to the frontline for a new documentary.

Speaking on 'The Real Crown', Sir Mike said: "What goes on in those audiences and who says what to whom remains for the two people involved, and I will break the rule about not divulging what goes on on this one occasion."

"She was very clear. She said, 'My grandsons have taken my shilling, therefore they must do their duty.' And that was that."

"But it was decided that William as heir to the heir, the risk is too great."

"But for his younger brother, the risk was acceptable".

Harry has spoken how he fought hard for permission to serve his country with his fellow soldiers, eventually going on to serve two tours of Afghanistan.

But Sir Michael's comments also play into Prince Harry's narrative that he feels he lived his life in his elder brother's shadow.

In Prince Harry's memoir, Spare, he suggests officials saw him as more dispensable than Prince William, who would one day be King.

It is understood Prince William was disappointed he wasn't allowed to serve on the frontline, but he did make a secret visit to the war-torn country in 2008.

Sir Mike Jackson claims the late Queen told him Prince William and Prince Harry must "do their duty".

Queen Elizabeth II was a symbol of duty, and it appears the late monarch was keen for her grandsons to prove themselves as assets to the Royal Family.

There are parallels with King Charles and Prince Andrew's experience serving in the armed forces.

King Charles, when he was Prince of Wales, was not allowed to serve on the front line of the Falklands War, whereas his brother, Prince Andrew, was.

Both Prince Harry and Prince Andrew grew up in the shadow of their older siblings and both, for very different reasons, are no longer working members of the Royal Family.

I suspect today's revelations will ruffle a few feathers behind palace gates, because the Royal Family values their privacy above all.

The extraordinary break in royal protocol by an ex-army boss, trusted with national security information, has sparked a debate.

We must wait for the full context to understand exactly why Sir Mike Jackson chose to disclose the late Queen's words.