LONDON - Listen for any promise to 'obey' in the wedding vows.

And look for the royal couple emblazoned on the side of souvenir teacups collected for years to come.

But don't, a prominent expert tells QMI Agency, expect the union of Prince William and Kate Middleton to become historic.

"It's not going to change the course of history," notes author Deborah McCoy, who's written a number of books on those, down through the centuries, who've taken the matrimonial plunge.

The author of titles like World's Most Unforgettable Weddings -- Love, Lust Money and Madness, Weddings A-Z and Elegant Weddings and the Budget Savvy Bride, says this Friday's event may not even be one of the most memorable.

Other marriages have seen the birth of a new religion and prompted the French revolution.

Though the Florida-based writer and wedding planner trainer does expect this event to have some spectacular and note-worthy moments -- as well as be overwhelmingly romantic.

"I wonder about the vows," she says, noting women around the world will listen whether Middleton promises to 'obey' her new husband.

The history of that promise, says McCoy, is not a total commitment to obey all commands issued by a husband, but instead, it originally was an assurance to submit to him in bed.

In the end, the ceremony may be remembered more for the block parties it kicks off across the UK, McCoy reasons.

Given tough economic times facing the UK, it's clear why the royals hope this wedding will be, says McCoy, "a little more down to earth."

Though it's likely not going to influence weddings to come.

She reasons: "For the normal, average person, spending less than $20,000, it's not going to have much impact."