She has made few gaffes over that time, the most significant being how the royal family mishandled the death of Diana, Princess of Wales. The public forgave their Queen but it took a wee while as Diana was dearly loved, if not by the royal family, then by the people of Britain and the Commonwealth.
Those 70 years have been trying at times, not only in the position but also with the trials and tribulations of the immediate and extended royal family, "the Firm".
There was a time in the 1950s when the Queen's marriage was under stress, the Duke still being a "man's man" and preferring the company of his naval mates to that of his family. Rumours have abounded over the years but the royal foot was firmly put down, things worked out and Andrew and Edward eventually turned up.
The Duke was always a bit of a rascal and caused the Queen embarrassment on many occasions with his ill-considered and racist comments, his dismissal of anyone he considered less important than him, which was just about everybody and his terrible driving habits. Road rules are for the peasants.
I have always felt a bit sorry for the Queen considering the weird bunch her brood are. I guess that's the price you pay if you are a distant mother and employ staff to virtually raise your children, as is the way in the Queen's class of society. In her case it has, over the years resulted in many public relations disasters and is still continuing with the antics of Andrew. Harry's immature and naïve behaviour of late has also been difficult for the Queen.
Some would say that this is the result if you marry your cousin and you are both descended from a closed royal British and European line of blueblood.
Thank goodness the modern royals have at least taken the effort to marry either the odd aristocrat or the occasional well-heeled commoner, getting some fresh genes into the tribe. Even an American. This of course, like a previous marriage to another American, Wallis Simpson, has proved disastrous for the Firm.
Americans, especially self-entitled ones, do not handle royal protocol and having to be second-place at all well. This of course results in the Firm sorting them out eventually.
The Queen must at times quietly cry herself to sleep over the antics of some of her descendants. It must break her heart not seeing Harry and his children. At the end of the day she is still human, still a grandmother and great-grandmother.
In the near future we will have a new Head of State. Will it be Charles reigning under another first name, George VII, a 73-year-old pensioner with a predilection for nature, talking to rocks and a wife no one likes or gets?
Or will he use what brain cells he still has and let his eldest child, William become King? William and Kate becoming King and Queen would be a public relations coup for the Firm. A picture post-card very popular couple.
Charles, being the selfish individual he has always been, will not stand aside unfortunately.
Whatever happens, the Firm will carry on. New Zealand will continue to have a person 12,000 miles away as Head of State for the time being at least.