Princess Elizabeth in Old Mother Red Riding Boots, Christmas 1944 (SWNS/Alamy)

At least a few times every year, I get emails and messages on social media asking about a photograph of a young Queen Elizabeth II wearing an interesting headpiece. I thought Halloween was an especially appropriate time to dedicate a post to this particular diadem, Princess Elizabeth’s Pantomime “Tiara.”

Princess Elizabeth and Princess Margaret in Aladdin, Christmas 1943 (AFP/Getty Images)

During World War II, Princess Elizabeth and Princess Margaret resided at Windsor Castle, away from London and the Blitz. On several Christmases during the war, the princesses took part in a special holiday pantomime performances. (For the non-Brits among us, pantomime [or just “panto”] is a Christmas tradition. A panto is usually a family-friendly play, often based on a traditional fairy tale or story, with broad comedy and various tropes throughout.)

In December 1941, the princesses starred in a production of Cinderella, with Margaret playing the title character and Elizabeth playing Prince Florizel. The performance was staged in the famed Waterloo Chamber at Windsor Castle.

Princess Elizabeth and Princess Margaret in Aladdin, Christmas 1943 (Getty Images)

Two years later, the princesses were part of a production of Aladdin at Windsor. Princess Elizabeth starred as Aladdin, and Princess Margaret played Princess Roxana.

In December 1944, the princesses acted in one more wartime panto: Old Mother Red Riding Boots.

Princess Elizabeth in Old Mother Red Riding Boots, Christmas 1944 (SWNS/Alamy)

The picture of Princess Elizabeth wearing the “tiara” comes from this pantomime. When you look closer at the image, you can tell that it’s not a genuine tiara, but rather a costume kokoshnik. (The pearls, though, are absolutely real!)

Other images from the panto show that Princess Margaret’s costume also included a tiara-like headdress. So there’s your tiara mystery solved, everybody! (And perhaps a bit of Halloween costume inspiration provided?)