On Friday, supporters of Brexit are planning to mark this one-time landmark day with protesting outside Parliament in protest that their prize has, for now, eluded them.
On Wednesday, Britain's departure will not be happening until April 12, if there is no deal, and May 22 if there is.
Yet, what happens in the House of Commons today, there is a possibility that the delay could stretch to a year.
If this threat is supposed to focus and persuade more lawmakers to back the Prime Minister's Brexit deal, it has, so far, not worked.
Without the backing of the Democratic Unionist Party (DUP), or the opposition Labor Party, May simply can not get over the line. Instead, the government has broken the deal into two parts in the hope of picking up more support.
Lawmakers wants to vote on the withdrawal agreement – which will enable the technical process of leaving the bloc.
This maneuver, announced by ministers yesterday, serves two purposes: Firstly, to get through to the commons Speaker, John Bercow, MPs (Members of Parliament) to vote on the deal for a third time – after two previous parliamentary defeats; and secondly, to make the deal more palatable for its critics.
When the UK leaves the EU with a deal, Brexit is extended to May 22. If it fails, the April 12 deadline is looming – and a no deal on that day is stalled on the table.
its current form.
Labor leader Jeremy Corbyn said offering his party's support would be akin to backing a "blindfold Brexit" because there would not be any opportunity to change the nature of the UK's future relationship with the EU.
It seems like a last-ditch attempt by the Prime Minister to finally deliver Brexit could backfire.
Which begs the question, why is May going ahead with the vote at all? Well, without a vote today the April 12 would have kicked in anyway – and would have been miraculously emerged.
This alternative option could still materialize – regardless of the outcome of today's vote – if and when lawmakers have a second round of indicative votes on Monday, which could signal support, potentially, for a soft Brexit plan.
This would be a must-have, as well as approved by Brussels – two very high bars.
Above all, by having a vote on the withdrawal agreement today, the Prime Minister is showing that it is trying to make it all right.
If, as expected, today's vote fails, then the UK is on the road to leave the EU on April 12.
There's no way to stop it on April 12 or accepting a longer delay of up to a year.
A year's delay would be the UK taking part in European elections on May 23, as well as triggering anger among Brexiteers.
Will this threat be to the minds of pro-Brexit Conservative lawmakers and the DUP who are holding together on the government in today's vote?
Britain's parliamentary deadlock, do not count on it.
Yesterday, the EU's chief negotiator Michel Barnier has been reported to be "the most plausible outcome"