Pictured: Prince Andrew and Queen Elizabeth II at the Royal Windsor Horse Show in 2017
As Tuesday night's televised election debate unfolded, there was mounting dismay at Buckingham Palace – and on the other side of the world.
At issue was not the responses to the question of whether the monarchy was fit for purpose, though it was telling that Jeremy Corbyn's answer – 'needs a bit of improvement' – got a much warmer studio reaction than Boris Johnson's line about the monarchy being 'beyond reproach'.
What really set off alarms across the Royal Household – and in Auckland, where the Prince of Wales was continuing his tour of New Zealand – was the simple fact that the monarchy was surfacing as a general election issue at all.
Throughout the Queen's reign, it has been a cast-iron rule that the Royal Family keep their heads down during election campaigns.
They can go about their business but they must avoid making headlines until the polls have closed and a winner can be summoned to the Palace.
That is how democracy works under a constitutional monarchy.
It is the reason why the Queen apologised to the then prime minister, John Major, when the breakdown of the marriage of the Duke and Duchess of York gatecrashed the general election campaign in 1992 – the year the Queen called her 'annus horribilis'.
Pictured: Queen Elizabeth II and Prince Andrew attend Ladies Day at Royal Ascot in June
Some Labour campaigners still cite all that deflected media coverage as a factor in Neil Kinnock's narrow defeat. That, however, was nothing compared to the detonation after Saturday night's BBC2 Newsnight interview in which the Duke of York attempted to explain his friendship with a convicted paedophile – and precipitated one of the gravest royal crises of the Queen's reign.
As a result, the election has now been relegated to the '…and in other news' section of most bulletins.
Tuesday's Johnson v Corbyn TV debate simply brought matters to a head.
The headlines had been dreadful for days. The corrosive effect of sponsors – including the royal accountants, KPMG – abandoning the duke's cherished [email protected] business initiative was just the start.
Far more wounding was the news that certain royal patronages were considering cutting their royal links.
It is patronages that underpin the royal role of those members of the Royal Family who are not in the line of succession. For the duke, they were his entire raison d'etre.
I understand that there was particular dismay when it emerged that the list of wavering charities included the Outward Bound Trust.
This was a much-loved patronage of the Duke of Edinburgh, a stalwart of the organisation since 1953, the year of the Coronation.
On Prince Philip's watch, the trust has expanded to more than 30 countries.
The Duke of York became involved 20 years ago as chair of the trustees and succeeded his father as patron eight months ago. His daughter, Princess Beatrice, sits on the board. For a charity so close to royal hearts to consider severing its royal links was profoundly worrying.
As Tuesday night's televised election debate unfolded, there was mounting dismay at Buckingham Palace, writes Robert Hardman
Tuesday's election debate, then, was the final straw.
Although the Duke of York's statement suggests that his retreat from the public stage has been his own idea, the decision had already been reached in telephone discussions between the Queen and the Prince of Wales.
It has been reported that the 93-year-old monarch had