Reginald Davis, 92, began his photography career with the Royal Navy during the Second World War. In 1949, he joined the Daily Express as a photojournalist who covered overnight news stories. Soon after, he began receiving assignments to shoot celebrities at red carpet events such as film premieres.

In 1959, Davis was tasked with taking photographs of Queen Elizabeth II and that's when he found his true calling. For the remainder of his career, the photographer travelled all over the world accompanying royal families on tours and state visits, and capturing some very special moments.

After nearly 50 years of taking exclusive photographs of some the world's most beloved film stars and royals, Davis penned a book, My Life Photographing Royalty And The Famous, in which he shares intimate behind-the-lens details about his glamorous and fascinating subjects.

Ahead of his book release, Davis sat down for a chat with the Daily Express and touched on his experience working so closely with the Queen and his favorite royals to photograph.

Davis told the Daily Express that "the most difficult royal" he ever photographed was Princess Grace of Monaco. The actress-turned-royal apparently "only agreed to a private audience because I had previously had a private audience with the Queen," Davis explained.

"Everyone wanted to shoot Grace," he continued. "She was such an attractive woman, why be so haughty, arrogant and awkward?"

"Of course, you'd never know that from looking at her face" he said. "[In the photo] she seems every inch the relaxed, happy mother," he added.

Not too far behind Princess Grace was Princess Anne.

"Princess Anne had a reputation for being difficult but I prided myself on putting my subjects at ease," Davis said proudly.

"She was perfectly happy to lie on the grass for me but when I asked if she would take a piece of straw and put it in her mouth, she replied: "I'm not that type of girl!"

As for his favorite royal to shoot? "Definitely Princess Margaret," Davis said without hesitation. "She was just so vibrant - and had these beautiful azure eyes. She really was the Diana of her day - everything I took of her was in demand."

When asked about Prince Charles, Davis remarked that he has a good sense humor and proceeded to share a story of a funny encounter he had with the prince at Badminton horse trials in 1976.

"This [the photo above] was at Badminton horse trials and I'd slept in," Davis recalls. "When I finally turned up at 11am he called out 'Hello Reg, I thought you decided to stay in bed all day' and I just picked up my camera and snapped away. He looks good here, it rather suits him."

Davis considers himself "very lucky" to have had so many opportunities to take pictures of the royal family. One of his most memorable shots was taken at Windsor Palace in 1969.

The photo featured the Queen, Prince Philip, Princes Charles, Andrew, Edward and Princess Anne sitting on a Persian rug in the garden.

"In 1969 I had been invited to Windsor Castle to photograph the family in the gardens. I had this idea of sitting them all on the grass," Davis explained.

"However, as the ground was so wet I had to find something for them to sit on. All that I could find was a Persian rug. When Prince Philip saw it he remarked: 'Whatever is a Persian carpet doing in the middle of Windsor?' Thankfully the Queen eased the situation, saying to the two younger boys: 'Come along children, let's sit on the magic carpet and fly away....'"

Davis said that he liked to try some riskier ideas when photographing the royals, but he made sure to always save them for last. Prince Philip wasn't always keen on trying them out, but the Queen often "saved the day."

For more exclusive photographs and stories about the royals and classic Hollywood stars, grab a copy of Davis' book on Amazon.