Buckingham Palace has been left reeling by the incident.

Whether it was unacceptable but unintentionally offensive, or malice – and everyone I have spoken to, including those who know Lady Susan, stresses it was the former – it is a sucker punch to the Royal Family’s attempts to project a modern monarchy.

It is why they moved so quickly to acknowledge how objectionable the comments were, issuing a statement in little more than two hours.

It is simply not acceptable in this day and age to dismiss what was said as a generational aberration.

As one senior former palace aide told me yesterday, it would have been unthinkable for Queen Elizabeth to have ever uttered anything similar.