It is a date famous for treachery when Roman Emperor Julius Caesar was stabbed to death by friends who turned out to be enemies.
But for Number 10 the famous prophecy to “beware the Ides of March” was originally ignored as they picked March 15 as the likely date to trigger Brexit.
Now the UK’s “independence day” is expected to be later in the month amid concerns from Government figures about the symbolism.
“We cannot have begun Brexit on the Ides of March. It doesn’t exactly send the right symbol,” said a baffled Government minister.
Theresa May has less than 20 days to choose from according to her own timetable for starting Brexit by triggering Article 50.
But the next fortnight is littered with potential embarrassments over which date will enter history as the moment Brexit formally begun.
March 17 and 18 is the Scottish National Party’s conference, where the hopes of Brexit finally bringing about the country’s independence will be high on the agenda.
March 25 is the 60th anniversary of the Treaty of Rome, effectively a celebration of the modern EU's creation. Brussels officials have asked for the date to be avoided.
Then there is the fallout from the Dutch elections, likely to dominate in Brussels after the March 15 vote and again raise questions about the EU’s future.
Britain is expected to leave the EU exactly two years on from whatever date is picked, meaning the hand of history is firmly on Number 10's shoulders.