It’s the most exclusive afternoon tea in England. It’s held in a palatial garden that is closed to the public. It offers the opportunity to rub shoulders with movers and shakers. And it is free.

There’s just one catch. You need an invitation from Queen Elizabeth II. No amount of blarney on the gate will get you in.

The Buckingham Palace Garden Party draws ordinary citizens from around the country. Guests are chosen for their contribution to the community, from charity workers through civic dignitaries to veterans and members of the armed forces.

“I was surprised to get so close to the queen,” said Mary Wenman, a local councilor from Burry Port, in South Wales. The monarch passed within touching distance of Wenman, who was invited for her part in helping to raise almost 300,000 pounds ($500,000) to restore the Burry Port Memorial Park.

Not everyone is as deserving: I was invited as a member of the Association of American Correspondents in London.

Wenman was among 8,000 guests at the garden party on June 10, which was also attended by Kate Middleton, the duchess of Cambridge, and by the queen’s husband Prince Philip, who was celebrating his 93rd birthday. A group of guests sang “Happy Birthday” as he walked past.

Also attending were the duke of York, Princess Eugenie of York, the princess royal, the duke and duchess of Gloucester and the duke of Kent. The queen was wearing a Stewart Parvin powder blue Jacquard coat and dress, with a hat by Rachel Trevor Morgan. The duchess of Cambridge was in a knee-length dress from Alexander McQueen.

One of the pleasures of the garden party is that security is almost invisible. There are no barriers. Distinguished-looking Gentlemen of Arms, wearing top hats and tails, simply ask guests if they would not mind forming lanes through which the royal family might walk.

The afternoon starts before 3 p.m. with queues outside the palace gates. Guests are required to show their invitations and passports to uniformed policemen. You then stroll through the Quadrangle and the Music Room to the garden, which — at 17 hectares (42 acres) — is the largest in London. About 320 different types of wildflowers grow here.

It’s down a few steps to the lawn. On your left, refreshments are served across long buffet tables in a tent. Smiling women, their hair tied tight in buns, hand out about 27,000 cups of tea, 20,000 sandwiches and 20,000 slices of cake.

No alcohol is available. This week, the sandwiches included cucumber, egg and cress, and ham and tomato. There were slices of cake and raspberry or strawberry tarts; tea, iced coffee, water or lemon barley water; and tubs of Marshfield Farm Ice Cream. The event is catered by Ampersand.

Everyone queues dutifully for refreshments, just as guests obediently form the two lanes for the members of the royal family to make their way across the lawn to their own tea tent, which has a small fence around it. The queen emerges from the palace at exactly 4 p.m., when one of two bands (from the Rifles and the King’s Division) strikes up the national anthem.

It takes 30 minutes for the short walk as the royals are introduced to ordinary guests along the way. Opposite me, a young woman fainted. The duchess of Cambridge — the late Princess Diana’s successor in the popularity stakes — hurried across to see if she was all right.

The members of the family walk back to the palace at about 5:30 p.m. and the party finishes at 6 p.m. The queen hosts at least three such events at Buckingham Palace each year and one at Holyroodhouse in Edinburgh. More than 30,000 people attend.

While that might sound a large number, most Britons never get the chance to attend. For many of those that do, it is an event to boast about in the weeks before and the years after.

It’s heartening to spend an afternoon in an artificial world, where everyone is dressed beautifully and behaves so well. It is a bubble of good manners where no one needs to be told twice what to do or what not to do.

Except when it comes to cameras. Photography is banned and yet the ubiquity of mobile phones (which “should be switched off”) means a lot of pictures are being taken. One policeman at the gate advised a guest to wait until no one was looking.

I stuck by the rules.

That’s why there is no selfie of me with the Queen.

Next time.

(Richard Vines is the chief food critic for Bloomberg. Opinions expressed are his own. Follow him on Twitter @richardvines)