How will Queen Elizabeth's reign be remembered?

STORY: (Princess Elizabeth, giving 21st birthday broadcast address) "I declare before you all that my whole life, whether it be long or short, shall be devoted to your service and to the service of our great imperial family to which we all belong."

How will Queen Elizabeth's reign be remembered?

1. The longest-reigning British monarch

[Penny Junor, Royal biographer]

''I think history will look back at this second Elizabethan age and see a period of enormous change, our society has changed dramatically during the 70 years of her reign.''

[Anna Whitelock, History of Monarchy Professor]

''She's played very well exactly the role of a constitutional monarch. She's not got involved in politics. We barely know her. I mean, she's the most charismatic sort of photographed most famous woman in the world, but she's also very enigmatic. We hardly know her. And I think being able to stay above politics, but seen as relevant and respected has been really important.''

2. A second 'golden age' for Britain?

Queen Elizabeth II's reign has often been compared

to that of her namesake, Elizabeth I

who ruled England over 400 years ago

in what is considered one of the country's greatest periods

"Some people have expressed the hope that my reign may mark a new Elizabethan age...Frankly, I do not myself feel at all like my great Tudor forbear." - Queen Elizabeth in her 1953 Christmas broadcast

[Anna Whitelock, History of Monarchy Professor]

"There's no doubt that she will be up there as one of the greatest monarchs, not just for her longevity, but for the, you know, the period of change which she has witnessed. And of course, like Elizabeth the first, you know, that Elizabethan age is also associated with great explorers and scientists and, you know, a dramatist like Shakespeare. And I think, of course, we can look back to the current Queen's reign and think about explorers and adventurers and scientists and so on, who will also be associated with that period. So I think equally seminal for, for Britain and also Britain's place in the world.''

3. Soft Power

The British sovereign now has few practical powers constitutionally

and is expected to be non-partisan

But historians say Queen Elizabeth has wielded 'soft' power

and made the monarchy a unifying, focal point for the nation

[Anna Whitelock, History of Monarchy Professor]

''The definition of success for any monarch over time is to preserve the monarchy and ensure the succession with that is the primary job. And that's what she's done. She's maintained the monarchy through a period of unprecedented change, and she's also ensured a line of succession."

[Matthew Dennison, Biographer and Historian]

''I hope that she will be remembered as somebody who, in terms of public service, was a very good person. I think there is there is great goodness in such an extraordinary glittering inheritance that somehow doesn't turn your head, but appears on a daily basis to remind you of the value and privilege of service.''