Thursday is a big day for the Queen as she celebrates her 96 birthday in what is her Platinum Jubilee year.
No doubt it will be a special day for Her Majesty, who is now Britain's longest-reigning monarch.
Her time as head of state has seen the Queen devote her life to royal duty and service to the country.
And it stems back to an emotional pledge she made on her 21st birthday - more than 70 years ago.
On that day - April 21, 1947 - the Queen, who was then Princess Elizabeth, was on tour with her parents and younger sister Princess Margaret in South Africa.
To mark her landmark birthday, she gave a speech on the radio from Cape Town, which was broadcast across the Commonwealth.
In the speech, she thanked people for their birthday wishes and spoke fondly of her time in South Africa and her coming of age.
And as she approached the end of her speech, she made an important promise saying: "I declare before you all that my whole life whether it be long or short shall be devoted to your service and the service of our great imperial family to which we all belong."
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Just five years after making that speech, Elizabeth became Queen - and it seems to be a promise she has kept until this day.
In fact, just last month she referenced the speech in her annual Commonwealth Day message.
Although the Queen did not attend the annual Commonwealth Day service at Westminster Abbey due to mobility issues, she still released her yearly message.
And in it this year, she said: "In this year of my Platinum Jubilee, it has given me pleasure to renew the promise I made in 1947, that my life will always be devoted in service.
The Queen has faced increasing issues with her mobility in recent months, leaving her “on certain days” struggling to get about, according to palace sources.
Royal aides have in recent weeks remarked how the Queen has "good days and less good days", as it emerged how she has been unable to walk her dogs for the last six months.
In February, she acknowledged her frail condition for the first time during a royal engagement at Windsor Castle.
The Queen told visiting military officials: “As you can see, I can’t move.”
