Princess Margaret asked her photographer husband to capture this picture of four royal mothers and their babies as a memento for the royal obstetrician who delivered the infants within two months of each other in 1964.

Snowdon/Royal Collection Trust

CNN —

As Queen for 70 years, Elizabeth II was probably one of the most photographed women in history.

Yet almost two years after her death, new pictures of Britain’s longest-reigning monarch have emerged for an exhibition opening at Buckingham Palace this week.

Among the most striking is a touching image from 1964 of four royal mothers and their babies – including the Queen and her youngest son, Prince Edward.

Alongside them are the Queen’s sister, Princess Margaret, plus Princess Alexandra and the Duchess of Kent, all holding their newborn babies.

The never-before-seen image was taken by Princess Margaret’s then-husband, photographer Antony Armstrong-Jones – or Lord Snowdon as he was known as then – as a personal thanks for the royal obstetrician who delivered the four babies within two months of that year.

A wartime picture of the then Princess Elizabeth in 1942 forms part of the new exhibition.

Cecil Beaton/Royal Collection Trust

Shown alongside it is a handwritten letter from Princess Margaret to her sister in which she asks “Darling Lilibet” to sign a print “as a souvenir of an extraordinary two months of delivery.”

“Royal Portraits: A Century of Photography,” which opened in The King’s Gallery of the palace on Friday, has more than 150 items from the Royal Collection and Royal Archives, which chart the evolution of royal portrait photography since the 1920s.

The Royal Family at Royal Lodge, 1943, conveying a reassuring sense of domesticity and calm during the war.

Cecil Beaton/Royal Collection Trust

Also on show for the first time are several wartime images taken by Cecil Beaton, who captured the royal family on camera over six decades.

Among them is one of King George VI and Queen Elizabeth inspecting bomb damage at the palace in 1940, while another shows them with their two daughters – Elizabeth and Margaret – around the King’s desk at the Royal Lodge in Windsor.

King George VI and Queen Elizabeth look comfortingly at each other a they survey the debris after bombing damaged Buckingham Palace in 1940.

Cecil Beaton/Royal Collection Trust

Proofs of Queen Elizabeth II and Prince Philip on Coronation Day, 1953.

Cecil Beaton/Royal Collection Trust

Handwritten note on the use of some coronation photographs, 1953, which features in the exhibition alongside the above contact sheet.

Royal Collection Trust

Beaton was the official photographer for Elizabeth’s coronation in 1953.

The exhibition features a contact sheet of proofs of the coronation sitting, alongside a note from Martin Charteris, the Queen’s assistant private secretary, recommending to Prince Philip which images should be sent to the royal family and maids of honor.

The picture that was subsequently chosen and sent to the Queen Mother can also be seen, signed by both the Queen, her husband and Beaton.

In a week where many headlines were made about the new official painting of the King, the exhibition offers an altogether different view of Charles.

It features a black and white shot of Charles, then a young prince, alongside his sister, Princess Anne, in 1956.

The current king as a child alongside his younger sister Princess Anne in 1956.

Antony Armstrong-Jones/Royal Collection Trust

There are numerous official photographs taken to mark royal birthdays, including a portrait by Beaton of Princess Margaret for her 25th birthday – together with her dog Pippin.

Separately, she and her sister, the Queen, can be seen laughing and talking in a contact sheet of images shot by Norman Parkinson on the occasion of their mother’s 80th birthday.

Princess Margaret as captured by her then-husband Lord Snowdon in 1967.

Snowdon/Royal Collection Trust

Another highlight is the earliest surviving color print of a member of the royal family. Taken in 1935 by pioneering female photographer Madame Yevonde, it shows Princess Alice, Duchess of Gloucester – sister-in-law to King George VI and Edward VIII – on her wedding day.

The exhibition, which runs until October, charts the innovations in portraiture, featuring Andy Warhol’s 1985 image of the Queen sprinkled with diamond dust and Rankin’s 2001 photograph of the smiling monarch, superimposed against the union flag.

Less traditional portraits, like this one done by Andy Warhol, also form part of the exhibition.

Todd-White Art Photography/Ben Fitzpatrick/Royal Collection Trust

The exhibition runs until October.

Todd-White Art Photography/Ben Fitzpatrick/Royal Collection Trust

Meanwhile, Paolo Roversi’s memorable 40th birthday portrait of the Princess of Wales, shows Catherine bearing a striking resemblance to Alexandra, Princess of Wales, by Franz Xaver Winterhalter in 1864.

The Princess of Wales, then the Duchess of Cambridge, photographed to mark her 40th birthday.

Paolo Roversi/Royal Collection Trust