Behind The Scenes: A Royal Birthday Bash

Written for CBSNews.com by London celebrity journalist Neil Sean.

This was is the scene at Highgrove House, the country home of HRH Prince Charles, as the staff and his most close friends get ready to celebrate his 60th Birthday.

But what treats can a Royal Prince have in store?

Firstly, the party at the Gloucestershire estate has been put together by Charles' loyal wife the Duchess of Cornwall and his sons, Princes William & Harry. All three were instrumental in making this a night to remember.

A source reveals, "It's the first time really that all three have joined up in such a way, but they are the ones that know the Prince best - his likes and dislikes - music, fun, and of course a way of showing their love."

The event will be attended by the likes of rocker Stewart and his wife Penny Lancaster, Dames like Judi Dench and Maggie Smith, and "Absolutely Fabulous" star Joanna Lumley, all feasting on the finest food and wine.

So will the Royal girls be there? We're talking of course about Kate Middleton and Chelsy Davy. Both have been invited and both have presents for the Prince.

William and Kate are as strong as ever after a bit of a wobble (she seemed to upset her man after been pictured at a roller disco in hot pants and top), while Chelsy Davy is the leader in the relationship with flame-haired Harry.

(CBS)

Of Chelsy, a source tells me, "She knows that she wants her own life, too. She is not overtly that impressed or shall we say concerned about all that Royal procedure stuff, and treats Harry so much than just a boyfriend. They are best friends, too … which makes him so happy."

Of course, all eyes will be on what the girls are wearing, and make no mistake: there is a glint of green in each girl's eyes as they wait to see who steals all the front tabloid pages and magazine covers. A source added, "It's like a scene out of 'Desperate Housewives' … they know they both have to scrub up well."

Earlier in the week, Prince Charles enjoyed a star-studded night at a West London theatre in which all his favorite comedians came out by Royal command to play - if you like, performing as modern-day court jesters.

Joan Rivers, always a Royal favorite, told me that Camilla is a huge fan of her home shopping skin care range, before going on to storm the show with her quips about getting old and why she wears something to suit her age now … a shroud.

The Royal Couple almost fell off their red plush seats as funnyman Robin Williams delighted them with his first stand-up stage show in 25 years. His routine was as spiky as he dared. He told my source, "I have no auto button and don't know when to stop, but I think they enjoyed it."

They did. With tears of laughter in his eyes, Prince Charles departed knowing that his favorite lineup of comedy has created the best TV line up in many years.

(AP Photo/Alastair Grant, Pool)

What about the Prince's thoughts on becoming King? In a recent TV documentary that has done wonders to re-establish him as a credible force here in the U.K., he admitted that it might be some time until the job was his.

But I can reveal the Prince has never been happier. He is a far more relaxed Prince of Wales, and loves having his wife Camilla at his side. A source tells me that only she "can swing his moods into something more human-like when all he can see are black clouds."

Princes William and Harry are a huge source of joy and happiness also. Prince Charles knows that as a parent he was watched like a hawk to see if he would be as cold and distant as previous royal fathers, but his sons always greet their "Pa" (as they call him) with a huge hug and a kiss. He always smiles at that.

Let's not forget also the Diana effect on his life, something that until now has not really been mentioned. In private he knows that she altered the way he looks at life and made him connect and appear more warm in public. According to palace moles, he has nothing but praise for his former wife as a mother (something that Royal fans must be thrilled to learn).

So what next?

Well, after all the celebrations, the Prince has no plans to slow down. He told a source, "I feel more active now than ever before, and I think I can find a way to do so much good in the world." He also likes meeting the public now more than ever, and is even warmer if his wife Camilla gets a welcome reception, too.

Will Camilla ever be his Queen? You bet. That is the plan, and despite what everyone says, her real title should be the Princess of Wales (but as we all know there is a reason for a new established title for her). Does she want to be Queen? The source adds, "If it makes him happy. She is too simple as that."

So as the party gears up, I hear that Rod and his band may have a secret backing singer lined up for the night. Would we dare to suggest that it's Camilla? I'll keep you posted but while Highgrove buzzes with one of the decade's glitziest parties ever given by the royals, one thing is for sure: Prince Charles may have hit the Big Six-Oh, but he is more relevant now than ever before. Happy Birthday, Sir!