WASHINGTON, Nov 18 (Reuters) - Is President George W. Bush's visit to Britain the first state visit ever by a U.S. president to the United Kingdom?

It depends upon whom you ask.

Yes, said Buckingham Palace.

"American presidents have visited the United Kingdom and stayed as guests of the monarch before, but never before have these visits been described as State Visits, due to a preferred lower-key ceremonial program," said an article in the official Buckingham Palace Web site.

A state visit is a formal affair with pomp and ceremony and a banquet. It is on a higher protocol level than, for instance, a working visit in which two leaders get together in a relatively low-key way to discuss foreign policy issues.

What about Ronald Reagan's 1982 visit? The U.S. State Department's Web site describes it thusly: "State visit; met with Queen Elizabeth II and Prime Minister Thatcher. Addressed Parliament."

But aboard Air Force One on the flight to London, White House spokeswoman Claire Buchan said Reagan's was not a state visit.

"The queen invited President Reagan, but it was not a state visit. The last state visit was Woodrow Wilson, in 1918," she said.

Well, what about the Wilson visit? The State Department Web site did not describe it as a state visit: "December 26-31, 1918.... Met with Prime Minister Lloyd George and King George V."

By the end of the day, U.S. officials were conceding that if Buckingham Palace said it was the first state visit ever, then the palace must be right.