[wagglebee]

Well, she is Catholic and she is the British equivalent of "First Lady"

The tradition is that a Catholic QUEEN can wear white, this applies to either the regent or the Catholic wife of a Catholic king.

Mrs. Blair is the wife of the Prime Minister, equivalencies are irrelevant as his very office is that of PRIME Minister to a king or queen. The argument may have worked with an American first lady; however, John F. Kennedys was the only Catholic president and Mrs. Kennedy (also a Catholic) wore the traditional black when meeting Pope John XXII.

[Schwaeky]

an obvious blunder, as a Catholic and wife of head of state who was likewise Catholic (in a nation that has no royalty) she would have been within her rights under protocol to wear white...