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The Queen of England doesn't write checks. It's not that she's worried about holding up the line at the local Piggly Wiggly, of course, but for a uniquely royal reason.

England's royal family is not allowed to give out autographs. It's not that they don't want to give their fans a memento, but because, as British paper The Express reports, the long-standing rule is in place to avoid forgery of their signatures. Sadly, there are some people in the world who would get up to no good if given a sample of royal handwriting.

Typically these days, if you ask a member of the family to sign your Queen Elizabeth tea towel, they'll apologetically state something like, "Sorry, they don't allow me to do that." While princess-to-be Meghan Markle has figured out a clever workaround that let her give a fan a souvenir without breaking the royal rule and Prince Charles once broke protocol to sign a note for a young flood, it's safer to ask for a selfie, which doesn't breach royal protocol.

WATCH: This Is the One Day of the Week Queen Elizabeth Carries Cash in Her Purse

Reader's Digest points out that there may be another reason that you won't find the Queen or Kate Middleton or Prince Harry writing a check any time soon—most people won't cash the checks. Instead, royal watchers tend to keep them as souvenirs. It's a nice keepsake, of course, but writing checks that may-or-may-not be cashed, can wreak havoc on the royal finances. According to Reader's Digest, both Queen Elizabeth II and her mother, Queen Elizabeth, The Queen Mother, have run afoul of the royal bankers in the past for drafting checks that were never cashed. The checks were such popular keepsakes that you can still find them for auction on eBay on occasion. Apparently, the Queen Mother wrote so many checks that went uncashed, that she had an overdraft of £4 million after she passed away, which her daughter had to settle. Guess the royal family will have to stick to paying for their groceries in cash, or if they can't bear to pay with banknotes bearing the Queen's face, there's undoubtedly a royal credit card floating around Windsor Castle.