When Ken Wharfe was hired in 1986 to work as Prince William's protection officer, it's fair to say his first day of work was more nerve-wracking than most.
Driving up to the imposing gates of their Sandringham estate in Norfolk Ken tells Now To Love it was "quite a nervous prospect meeting the Princess [and her sons]."
He was escorted into the White Room and standing before him was Princess Diana, Prince William, who was five at the time, and a three-year-old Prince Harry.
Any jitters the royal bodyguard may have had were soon put at ease thanks to the very normal and chaotic scene that greeted him.
"William was attempting to play a piano and Harry was stood on a small coffee table, de-stemming a vase of lilies. And the first thing Diana said to me was, 'I don't envy you looking after my two sons! They can be a ruddy nuisance!'"
"William turned around and said, 'We're not a ruddy nuisance!' In what I refer to as that Just William Way," Ken shares with us.
"At which point Harry fell off his table and Diana said, 'Come here, both of you!' And they ran off and I hadn't said a word! I thought to myself, this is a pretty good start. If it's going to be like this, it will certainly be fun. And it was!"
"It was a great period in history for me in working with a woman that did change the face of the monarchy. She was an incredibly fun person."
In this exclusive interview as we approach what would have been her 60th birthday, Ken shares what Princess Diana was really like...
In 1987, Ken's line of work became even more serious when he was transferred to become Princess Diana's bodyguard.
While having the job description of keeping the world's most famous woman safe is no doubt a daunting prospect, the 70-year-old credits his "tremendous" boss for making his role easier.
"She accepted the role that we had. Fortunately there was a chemistry there, I like to think we got on together as a boss-employee," the bodyguard explains.
Ken says the key to keeping Diana safe was open lines of communication between the princess and her team – something the mother-of-two was great at.
"She would write on a handwritten note the week's instructions so one knew exactly what we were doing. She was very forthcoming in involving me with what she was doing, that enabled me to put in place the very best protection for her."
"In all the years that I worked for her, I can very confidently say that never once the security compromised. Simply because of her involvement, she acknowledged that everyone in the palace was an important part to the success of the work that she was doing. There were no barriers; everybody became part of this Diana magic," he adds.
Despite the enormous size of her team, Diana had an inherit ability to make everyone feel special.
"She was very generous, if it was your birthday you always received a card and a generous gift. That was Diana!"
WATCH: A look back at the loves of Diana's life. Post continues after the post...
When she wasn't working, Diana was always surrounded by friends and family.
"She was a great socialite, she'd speak to the butler or the chef or invite friends around. I remember endless journeys we had travelling down to Highgrove and you'd talk about anything," Ken fondly remembers.
"She was very up on current affairs and liked to know what was going on in the world. Behind closed doors, she was as you would see her publicly."
"Her character and sense of humour was very lively. How at times she maintained that given the difficulties of her own relationship, I don't know, but she did!"
As a full-time working royal, Diana took her job and duty to The Queen very seriously. Her empathetic style and the issues she championed were unlike anything the Royal Family had ever seen before.
Understandably, the public became enamoured with her.
"It was this popularity of Diana that was a real problem for her husband and other members of the royal family, and they never really addressed that," Ken tells.
"The one thing Diana craved and very rarely got and she said so, was to be told she'd done well. But Diana never really got any thanks from anyone within in the royal family."
Despite the rising tensions within the House of Windsor, Ken says Diana's relationship with The Queen "was second to none."
"That was Diana's purpose in life. She was there to represent The Queen and to do what she thought was the best. Diana's ultimate aim was to please and help the royal family," he claims.
When she decided to raise awareness for AIDS in the late eighties, Ken says it was "a real problem."
"I remember the Queen saying to Diana, 'Why do you want to get involved in something like that? Why don't you get involved in something nice?'" Ken claims.
Diana may never have received the praise she so desperately wanted but she did have alliances within the royal family.
"She liked Princess Margaret quite a lot. On a number of engagements she went with Princess Margaret and found a great deal of solace in discussing things with her," Ken shares.
"Despite rumours to the contrary, I think she admired The Duke of Edinburgh, who was very helpful to her during the troubles in her marriage."
Behind the pomp and pageantry of royal life, Diana's most important role was raising her two boys.
As their bodyguard, Ken was privileged to watch Prince William and Harry in their formative years and says Diana strived to raise them as "non-royal" as possible.
"The great thing was, Diana was insistent that the boys weren't kept royal and away from the workers. Diana respected everybody in the palace and there was a general free-for-all for William and Harry to wander around the palace and speak to everybody. Harry in particular was always mischievous," he reflects, before sharing a very hilarious incident involving a bathtub.
"My room was very near to the nursery and I was running a bath in the evening. Harry asked me what I was doing and I said: 'I'm just running a bath,'" he recalls.
"And he must have been six or seven, he disappeared to the kitchen and said, 'Is there anything I can put in Ken's bath?'"
"The chef gave him a bottle of food colouring and I came back for my bath and I had a completely red bath. And there's Harry standing around the corner, it was highly entertaining. They were great kids!"
WATCH: Princess Diana drops William off for her first day of school. Post continues after...
Her privileged life came with a very high cost and having to be guarded 24/7 was a constant struggle for Diana.
But even bodyguards can be persuaded to bend the rules and Ken reveals he once smuggled his boss to a secluded beach so she could go for a solo stroll.
"I remember giving Diana one of my radios and she walked off with her Michael Jackson jacket and I just went to the other end of the beach, the risk factor here was minimal because nobody knew we were there."
Everything was going to plan until his walkie-talked buzzed with a giggling Diana at the other end.
"After about 40 minutes, she called me on the radio and said, 'You never told me about the nudist beach!' I'd completely forgotten about it and Diana had stumbled in front of about half a dozen naked males all paddling in their birthday suits. Of course they didn't have a clue who this woman was."