The Queen is the most photographed woman in the world - but she's spent plenty of time behind the camera too

On the evening of her 90th birthday, as she and her immediate family settle down at Windsor Castle to a dinner hosted by the Prince of Wales, BBC1 viewers will have a chance to watch Elizabeth at 90 – a touching compilation of home movies filmed by the Queen and the Duke of Edinburgh, a good many of which have never before been seen outside royal circles.

But it’s not just the films themselves that are revealing; it’s seeing the reactions of senior family members as they watch long-forgotten footage and hearing them reflect about the familiar figure we see in it.

Six members of the royal family have been interviewed for the programme. One of them, Prince Harry, talks about how he still – metaphorically – has to pinch himself when, at family gatherings, he finds himself face to face with the Queen. Harry tells the programme, “I still view her more as the Queen than my grandmother. You have this huge amount of respect for your boss and I always view her as my boss, but occasionally as a grandmother.”

Another is Princess Alexandra, who recalls during the war years being given “invaluable” clothing hand-me-downs by her cousins Elizabeth and Margaret. “Because of the clothing coupons, it was quite difficult to get hold of clothes,” she says. “So they were very kind to me, my cousins – I think it was Princess Elizabeth mainly – they let me have one or two of their dresses.”

The programme’s producer/director, John Bridcut, has spent two years working on the project, delving into what he calls the Queen’s “extensive” collection of home movies. He’s been impressed, he says, by the quality of the camera- work – “the Queen’s is very steady” – and by the insights the footage offers into the affectionate closeness of a family who have sometimes been portrayed as being distant with each other.

The earliest footage dates from 1927. The Queen was a one-year-old princess. Her father, the then Duke of York, followed the instinct of every proud parent with a camera, with one important difference. He had a cine camera, a rare thing in a private home in those days, and it’s clear from the footage that both the future George VI and his wife were enthusiastic wielders of their whirring Rolleiflex, capturing sequence after sequence of Elizabeth and, subsequently, her younger sister Margaret.

“One of the chief things that emerges from the early footage,” Bridcut says, “is the incredible closeness of the sisters; it’s touching to see how strong that link was. You get a striking impression of the importance of the relationship.”

The footage moves through the decades: the 1930s, when her father unexpectedly became king; the 1940s, when Britain fought for its survival; the 1950s, with the premature death of George VI and the accession of Elizabeth II, who had to balance her duties as monarch with her role as a young mother with two small children, Charles and Anne; and the 1960s, the decade of social upheaval, when the Queen’s family expanded with the addition of two more sons, Andrew and Edward.

The footage captures a flavour of much of it, most especially the family moments, but also something of the working monarch, on tour in different parts of the world, sometimes operating the camera herself, more frequently caught in footage shot by her husband. Once again, according to Bridcut, it is the interpersonal warmth that is strikingly apparent, between husband and wife and mother and children. “There is a lot of teasing,” he says, “which is how affection is expressed within this family, rather – as with many people of the Queen’s generation – than by overt physical contact.”

It is footage that, of course, was never intended to be widely seen. As a result, these are relatively unguarded moments that, Bridcut believes, reveal something of the “real” person behind the tightly disciplined figure to which we’ve become accustomed.

That individual is, by instinct, a contained and careful personality, sharp-eyed and watchful – someone who is constantly at the centre of attention but who dislikes too much of a “fuss”. That was evident last September when she became the United Kingdom’s longest-reigning monarch, passing the record set by her great-great grandmother, Queen Victoria.

Many wanted to celebrate then, but the Queen did not. It felt inappropriate to her to mark with any degree of satisfaction a milestone that had only been made possible because of the death, at the age of just 56, of her beloved father, George VI – a point the Princess Royal, Princess Anne, makes very poignantly in the film.

“Don’t forget, there’s a very double-edged sword. People tend to forget, when she passed the longest-reigning monarch, that was only because her father died so young. So you know for her that’s a very mixed blessing, and it’s a record that she would much rather not have been able to pass.”

Such was the Queen’s reluctance to acknowledge the landmark achievement that her staff had to be rather insistent in their encouragement that, yes, the public would expect to see her on the day, September 9th, when the longest-reigning record was broken.

There are no such inhibitions this time. A 90th birthday is a significant milestone in any life, even that of a monarch. And so on 21 April, the Queen will emerge from Windsor Castle for a stroll (“walkabout” in royal-speak) through the town centre to meet anyone who might just happen to gather there.

It will be pretty low-key. The main celebrations are being organised over three days in June around her official “Birthday Parade”, the annual military pageant better known as Trooping the Colour. But it seems a safe bet to expect that on Thursday – just as there was on her 80th birthday – there will be a Guards band conveniently placed in Windsor to play Happy Birthday to her. Ten years ago, it produced a momentary expression of delight, a look that seemed to say, “What, all this, just for me?”

And that, I think, having spent 18 years now reporting on the royal family for the BBC, revealed something fundamental about the person who is Elizabeth II. For all the grandeur of the position that she occupies, this is someone who, at heart, is remarkably down to earth. “Humble” is not a word that seems appropriate to the description of a hereditary monarch, yet there is – according to those who know her – a touching humility about this monarch.

It is, I believe, one of the keys to her success. It underpins her sense of duty, the undemonstrative decency of her approach to life, and the great regard in which she is held by those comfortable with a constitutional monarchy, and even by a very great many of those who are not.

Among the home movies that John Bridcut unearthed for a BBC documentary he made to mark the Queen’s Diamond Jubilee in 2012 was the first, previously unseen image of Elizabeth II after she succeeded to the throne. It was in a short sequence of cine film taken by her husband as they flew back to London from Kenya after hearing of George VI’s death. The camera swings around and there is Elizabeth, looking directly into the camera, composed but with a hint of vulnerability. It is a haunting image of a 25-year-old who was just embarking on a reign which, she knew, would set her apart for the remainder of her life.

She is now on the threshold of her 90th birthday. As she sits down to that birthday dinner with her family on 21 April, she will be able to look back on a reign that – for all the bumps along the way – has maintained the monarchy’s position at the very centre of national life throughout more than six decades of bewildering change. Doubtless a toast will be drunk by her family, among whom will be the United Kingdom’s next two kings, Charles and William. George, we must assume, will be in bed.

Elizabeth at 90: a Family Tribute is on Thursday 21st April at 9pm on BBC1