“Throughout all my life, and with all my heart, I shall strive to be worthy of your trust,” she declared.
She has kept her promise, through good times and bad, across seven decades which have brought personal heartache as well as joy, and seen the country change almost beyond recognition.
Yet one thing has remained constant – the Queen’s presence. Regal, serene, smiling, for tens of millions of her subjects there simply has never been a time when she was not there.
Many chapters of history have been written during her lifetime, and now she is to write one herself.
Today marks the day when she will overtake Queen Victoria’s 63 years and 216 days on the throne to become Britain’s longest-reigning monarch.
And how gloriously different a reign it is.
The picture history has left us of Victoria is one of sorrowful duty, of a monarch clad in the black of mourning for the last 40 years of her life after the death of her beloved Prince Albert, shut away and rarely seen by her subjects.
She was dubbed “The Widow of Windsor” in her seclusion and loss, and of all she said and wrote during that long reign, only a single short sentence resonates with us today, seeming as it does to sum up a character robbed of all joy by grief: “We are not amused.”
The picture of our Queen could not be more striking in its contrast. Her pleasure in meeting the public is plain, her smile as ready and warm as Victoria’s was absent, her ability to spread joy and enthusiasm unparalleled by any public figure, let alone head of state, who has come or gone these past 63 years.
Her wisdom and astuteness far outstrip Victoria’s.
Twelve prime mnisters, from Winston Churchill to David Cameron, have confided in her and relied upon her judgement.
She has been privy to the innermost secrets of her country’s gravest crises and greatest dangers, the dignified face of its most solemn state occasions, and proved the greatest ambassador Britain ever had.
Amid all this, she has been mother, grandmother and now great-grandmother, steering the House of Windsor through its own crises, and ensuring its continued place in the public’s affections by virtue of her own unstinting hard work and warmth.
Nowhere has that affection been expressed louder and longer than here in Yorkshire.
The county fell in love with the Queen before she even came to the throne, on July 6 1949 to be precise, when the then Princess Elizabeth arrived in Halifax at the start of her first official tour of the county.
The glamorous 23-year-old princess, and her dashing naval officer husband, brought a splash of colour to a Yorkshire steeped in austerity and still getting to grips with both repairing the bomb-damage and healing the emotional scars of war.
The three days that followed were a heady round of wild enthusiasm, in which hundreds of thousands of people climbed and clung to every vantage point in Wakefield, Huddersfield, Leeds, Harrogate and York for a glimpse of their future Queen.
That tour set the tone for every one of the dozens of visits that have followed.
Her first official visit as monarch, in 1954, took her through Yorkshire’s industrial heartlands to the echoes of cheers.
Three years later she forged an enduring link with the county’s farming community with the first of many visits by her and her family to the Great Yorkshire Show.
The Queen must long ao have lost count of how many times she has heard the National Anthem sung. But as she cruises past this extraordinary milestone and on into the future, the line “Long to reign over us” surely has a special resonance for her, and for us all.