Lady Anne Glenconner played on the beach with Princess Elizabeth and Princess Margaret as a child and went to their birthday parties — but she never dreamed she would play a prominent role in Britain’s last coronation.

Lady Anne was one of six girls, the daughters of dukes or earls, chosen to be the queen’s Maids of Honor when Elizabeth ascended the throne on June 2, 1953. She was 19 to Elizabeth’s 27. As the Smithsonian Channel special “The Coronation” vividly illustrates, the Maids were the “Spice Girls” of the time, with plenty of media coverage — and there were plenty of procedures to follow.

They were “grilled” by the Duke of Norfolk on coronation etiquette and rehearsed the walk to the Abbey altar, with the Duchess of Norfolk subbing for Elizabeth II. Lady Anne was also fitted for a dress designed by Norman Hartnell, dressmaker to the Queen and the Queen Mother. Lady Anne, now a jolly 85, still has the “heavenly silk” creation, which she says isn’t in very good condition. The Smithsonian special also includes footage of the coronation, which was held at Westminster Abbey. The preparation was extensive, with 27 miles of seating built along the route from Buckingham Palace to the Abbey and 30,000 troops assembled from across the Commonwealth to march in salute. The Abbey was packed to the rafters with 8,000 guests and participants.

Lady Anne held the queen’s train as she stepped out of the royal, four-ton gold coach. “She was too beautiful for words,” says Lady Anne. And then there was a lot of standing, as the Archbishop of Canterbury enacted the coronation ritual. “The queen was very calm, which helped,” she says.

One of the pleasures of watching this show is hearing Queen Elizabeth herself weigh in with the BBC’s Alistair Bruce on everything from the coach she rode in (“horrible”) to the Imperial State Crown. She describes the crown as so heavy, “You can’t look down to read the speech, you have to take the speech up. Because if you did, your neck would break — it would fall off.” (According to the UK’s Radio Times, Bruce wasn’t allowed to ask Her Majesty any questions, only “to make observations and tacitly invite her to respond.”)

The entire coronation took about two hours, by Lady Anne’s estimate, and then it was a short ride back to the palace, where royal protocol fell by the wayside. “She took off her crown and put it on the table. Prince Charles took it,” Lady Anne says. “Luckily, a lady-in-waiting seized it. The queen thanked us and sat on her sofa. It was such a relief that it was over.”

Lady Anne is still pals with Queen Elizabeth. “I saw her this summer,” she says. “I do see her from time to time.”

“The Coronation” 8 p.m. Sunday on Smithsonian Channel