Royal Oops! See the Moment a Man's Phone Rings Just as He's Shaking Hands with Queen Elizabeth

PA Queen Elizabeth

There's a lot of protocol to follow when meeting Queen Elizabeth — and maybe silencing your phone should be added to the list!

When the Queen, 96, and Princess Anne made a surprise appearance on Friday to open the new 28-bed Thames Hospice building, the monarch was introduced to patient Pat White and her husband. But just as the husband and Queen started to shake hands after being introduced, his phone started ringing. He hurried to take it out of his suit pocket and end the call.

The Queen appeared to address the potentially awkward moment lightheartedly.

RELATED: 'Ma'am' Like 'Jam' — What Not to Do When Greeting the Queen and Royal Family Members

While there are rules for meeting members of the royal family, they often shrug off any mistakes or informalities. When Prince William and Kate Middleton visited Wales earlier this year, Nicky Hurst of Country Fare Wholefoods and Fine Cheeses went with a casual address instead of "Your Royal Highness" when the couple stopped by the cheese stand at Abergavenny Market.

"They are lovely," Hurst told PEOPLE. "I wasn't sure what they'd be like and what to call them in terms of their titles. I called them 'Kate' and 'Will,' and they were really relaxed."

But for the record: if you should be introduced to the Queen, the correct formal address is "Your Majesty." For any further address, you should call her "Ma'am," pronounced with a short "a," as in "jam." While it's perfectly acceptable to simply shake hands when being introduced to a royal, men may opt to do a slight neck bow (from the head only) while women do a small curtsy.

PA Queen Elizabeth on Friday

Accompanied by her daughter Princess Anne, the Queen was all smiles as she chatted with staff and volunteers during the tour of the facility.

Wearing a floral print dress and pearl accessories, the monarch moved around with the aide of a cane, which she has been using regularly since October due to her ongoing mobility issues. And of course, she didn't leave home without her trusty handbag on her arm.

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PA Queen Elizabeth and Princess Anne

Friday's outing marked Queen Elizabeth's fourth visit to the charity. She first opened Thames Hospice in Nov. 1987. In the last few years, it has been modernized and rebuilt on a new site following a huge $26 million fundraising effort.

Thames Hospice Chair of Trustees Jonathan Jones said afterwards, "Today's momentous visit builds upon a long-held association between the royal family and Thames Hospice. It is a huge privilege to welcome Her Majesty to officially open our facility and show how the charity continues to flourish 35 years on from the Queen's very first visit."