George W. and Laura Bush with Queen Elizabeth and Prince Philip at the White House in 2007. (Susan Biddle/The Washington Post)

D.C. protocol geeks will be throwing their weight around this week, smugly telling you why Wednesday’s state dinner for U.K. Prime Minister David Cameron isn’t a “state dinner” at all.

Why? Because “state dinners” and “state visits” are reserved for heads of state — and in the case of Great Britain, that’s still Queen Elizabeth, who had her most recent “state visit” to the White House in 2007.

British Prime Minister David Cameron and his wife Samantha in Scotland last year. (More Samantha Cameron photos) (Jeff J Mitchell/Getty Images)

So what Cameron, as head of government, and his stylish wife Samantha are coming for is techically called an “official visit,” complete with red carpet and a formal banquet that will certainly taste like a state dinner — but only a mere 19-gun salute.

Their visit will include the usual policy jawboning, but it’s also a diplomatic commercial: Brits are fanning across the globe to promote the 2012 Summer Olympics in London and the queen’s Diamond Jubilee celebration of her 60 years on the throne.

The Camerons will arrive in the U.S. Tuesday for a series of carefully orchestrated events and photo-ops. President Obama will take the prime minister to a first-round NCAA Tournament game Tuesdayin Dayton, Ohio, while the first ladies will stay here for an Olympics-themed event at American University with D.C. school kids. There’s a formal arrival ceremony Wednesday morning, and then that evening’s black-tie dinner.

No word yet on who scored an invitation. Given strong U.S.-British ties, the guest list is likely to have plenty of big names. When newly-elected Tony Blair came to Washington in 1998, the Clintons invited John F. Kennedy Jr., Barbra Streisand, Harrison Ford, Steven Spielberg and T om Hanks. For the queen’s visit five years ago, the Bushes included Itzhak Perlman, Nancy Reagan, Colin Powell, Henry Kissinger, Arnold Palmer, Peyton Manning, and, in honor of the queen’s equestrian tastes, that year’s Kentucky Derby-winning jockey, Calvin Borel.

Update: Damian Lewis of “Homeland” coming to state dinner, 3/12/11

Read earlier, from President Obama’s 2011 state visit in Britain:

Obama’s London visit comes amid British reckoning, 5/23/11

Michelle Obama wows Britain with high style, meets Kate Middleton, 5/25/11

Obama scores with better gifts for Queen Elizabeth, 5/24/11

How Obama bungled his toast to the queen, 5/27/11

From Queen Elizabeth’s 2007 state visit to Washington:

White tie and tiara: Queen’s visit brings uncommon glow to White House, 5/8/07