David Cameron has astonished Berlin by looking to make his controversial Europe speech on the same day that France and Germany stage lavish celebrations marking their postwar reconciliation.
To add to the diplomatic drama, Mr Cameron is considering making his speech in Germany on the day hundreds of French and German politicians gather in Berlin to mark the 50th anniversary of the Elysee treaty.
The office of Chancellor Angela Merkel is understood to be in direct contact with Downing Street about the preferred date. One senior German official said the timing was "quite extraordinary".
"It is insane," said Ulrike Gurot at the European Council on Foreign Relations. "Mr Cameron should have some decent respect. It is a sulky reaction, and an attempt to steal the headlines."
"Choosing the 50th anniversary of the most important treaty between France and Germany to make a big anti-EU speech is a grotesque perversion," added Denis MacShane, a former Labour Europe minister. "It's like a religious day for them."