Prince Philip's devastating reply when he was told his wife had become Queen

It's exactly 70 years to the day that Princess Elizabeth became our Queen.

On February 6, 1952, her father George VI died aged 56 and the then 25-year-old Elizabeth ascended to the throne.

The Queen was in Kenya with her husband Prince Philip, at the beginning of a huge royal tour of the Commonwealth. Technology at the time meant it took a long while for the sad news of the King's death to reach the royal party.

The Queen's aides first learnt of the news and grappled with how to tell their boss about her father's passing - which also meant that the throne was now her's.

In the end, they told Prince Philip, who then had the tough task of delivering the news to his wife.

The Queen with her late husband Prince Philip (Getty Images)

And according to Lady Pamela Hicks, the Queen's lady-in-waiting, Philip knew the Queen would be heartbroken on hearing the news.

In her book Daughter of Empire, Lady Pamela says that Martin Charteris, the Queen's private secretary “went in to tell Philip, who lifted his newspaper to cover his face in a gesture of despair, saying ‘This will be such a blow’.”

Love the royals? Sign up for the Mirror's daily newsletter to get all the latest news on the Queen, Charles, Kate, Wills, Meghan, Harry and the rest of The Firm. Click here to sign up .

The Queen and Philip in Kenya in 1952 (Mirrorpix via Getty Images)

The Queen with her beloved father George VI (Getty Images)

Philip then went to tell the Queen and aides watched as the couple walked back and forth through the garden.

What was said is a mystery but Pamela tells how afterwards the Queen “remained completely calm and said simply: ‘I am so sorry. This means we all have to go home.’”

The group began their hasty journey back to Britain on the royal BOAC Argonaut, refuelling in Libya where a black coat, handbag and shoes were delivered.

Philip was at the Queen's side for most of her reign (Tim Graham/Getty Images)

The Queen arrived back in mourning garb to meet dignitaries including Prime Minister Winston Churchill.

Since then, Her Majesty usually marks February 6, the day of her ascension, in private at Sandringham, where her father died.

Tomorrow will be especially poignant as it marks 70 years since that fateful day - but it will also be the first one without her husband Philip by her side who died aged 99 last April.