Queen Elizabeth has earned herself the title of Britain's longest serving monarch, occupying the throne for a staggering 67 years.
Since 1952, Her Majesty has maintained an incredibly busy schedule filled with whirlwind international tours, official engagements and more royal meet and greets than hot dinners.
But according to new reports from a royal insider, the Queen let one very important occasion slip her mind - namely, the birthday of her youngest son, Prince Edward.
Speaking about the Earl of Wessex - who is the fourth child of Queen Elizabeth and Prince Phillip - in a new Channel 5 documentary hosted by British journalist Jeremy Paxman, Edward's biographer Ingrid Seward described the prince's childhood at Buckingham Palace as "lonely" and isolated.
"One year on his birthday [in his twenties] he went to have breakfast with the Queen and nothing was said.
"No card, no present. She didn't know it was his birthday," Seward, who is the editor-in-chief of Majesty magazine, told the programme.
The noted royal writer previously revealed details of Edward's upbringing in her 2005 book Prince Edward: A Biography, which claimed the Queen's "heroic" son Andrew, who fought as an Admiral in the Falklands War aged 22, was her favourite child.
Royal historian Piers Brendon confirmed this claim during his appearance on Paxman on the Queen's Children, telling viewers Andrew's decision to skip university and join the navy "went down well" with Prince Phillip.
The researcher added his bravery and dedication to his country caused the Queen to develop '"a soft spot for him".
The Earl of Wessex, now 54, went on to marry Sophie Rhys-Jones - Countess of Wessex - in what is often referred to as "the least complicated royal romance of modern times".
The couple have two children, James, Viscount Severn and Lady Louise Windsor, but despite their scandal-free happily ever after Edward's relationship with his monarch mother does not appear to have improved.
Biographer Seward has also claimed the Queen confronted the youngest Windsor over his perceived "disloyalty" to Prince Andrew's wife, Sarah Ferguson.
Edward allegedly blamed Fergie for "making a fool of his brother" and blamed the former Duchess for leaking sensitive information about the royal family to the press.
Queen Elizabeth, who has largely remained fond of her fiery daughter-in-law, summoned Edward and "explained to him how unfair it was to accuse the Duchess of such disloyalty".