LONDON — The first indication that something was up in Downing Street came on Saturday morning, when senior staff got a call out of the blue asking them to come into the office for a special Easter Monday planning session.

Until the meeting called by “the chiefs” — a.k.a. Fiona Hill and Nick Timothy, Theresa May's co-chiefs of staff — almost nobody in Number 10 had any idea they were about to fight a snap general election. In a sign of how the prime minister operates, the news did not leak.

Most people inside the government had no idea for another 24 hours, when they attended cabinet Tuesday morning — or watched the news at just after 11 a.m. when the prime minister told the nation, from the steps of Number 10, that she was calling the election on June 8.

Some more astute ministers might have had an inkling late Monday, when news circulated in whips' circles that the prime minister would make an announcement. But even the government whips didn't know what it would be about, according to one Tory minister.

“The civil service was completely blindsided,” the minister said. “She kept it completely under wraps. She learned the lesson from Gordon Brown [the former Labour prime minister who famously contemplated an early election but decided against it]: If you’re going to do it, do it. She knows how to make a decision, that’s for sure.”

“The civil service was completely blindsided. She kept it completely under wraps” — Tory minister

May had made the decision while walking in Wales with her husband Philip last week, she told ITV’s political editor Robert Peston. “I thought about this long and hard, and came to the decision that to provide that certainty and stability for the future, that this was the way to do it, to have an election,” she said.

However, Tory MPs know the prime minister does not make decisions hastily. Her style is to weigh up all the facts before coming to a conclusion, which she then rarely if ever revisits. The fact that Australian election guru Lynton Crosby has already been signed up to oversee the campaign, according to one Conservative minister, points to far more serious planning than Number 10 have let on.

Crosby and his business partner Mark Textor will play leading roles in the campaign, working with Stephen Gilbert, who masterminded the Conservatives’ marginal election strategy in 2015 as head of campaigning, and party chairman Patrick McLoughlin.

The first poll carried out after the announcement pointed to a comfortable Tory win. The snap survey by ICM put the Tories on 46 percent, 21 points ahead of Labour on 25 percent.

If May was not confident of the numbers, she wouldn't be going for it, several Conservative MPs said. However, excited talk of a “landslide” has irritated some in government. “There are just too many parts of the country where we cannot win,” one senior MP said. “A majority like the Coalition’s [between the Conservatives and Liberal Democrats in 2010] would be one heck of a result. It’s about getting her own majority, not winning a landslide.”

'F*** off, I've got the mandate'

Ostensibly, the decision to bring forward the election is designed to strengthen May’s hand in the upcoming negotiations with Brussels by seeing off the threat from Labour, the Liberal Democrats, Scottish National Party and the House of Lords, who all pose a threat to the approval of her final exit package. Scottish First Minister Nicola Sturgeon said May’s goal was to wipe out opposition to a hard Brexit.

That was certainly how May made it sound outside Number 10.

“At this moment of enormous national significance there should be unity here in Westminster, but instead there is division," she said. "The country is coming together, but Westminster is not.”

A general election was needed, May said, because the U.K. had a “one-off chance,” after handing in its article 50 notice of leaving the EU, “while the European Union agrees its negotiating position and before the detailed talks begin.”

Among some pro-European Tory MPs there was quiet confidence that the move will finally strengthen their hand against the Brexit hardliners. May is not trying to break out of the problems caused by the opposition parties, but by the opposition within her own party who are increasingly open to the prospect of no deal with Brussels.

“At this moment of enormous national significance there should be unity here in Westminster, but instead there is division" — Theresa May

For May — who backed Remain because she feared Brexit’s economic consequences on the poor, according to one of her closest aides who spoke to POLITICO during the referendum campaign — no deal is almost unimaginable.

“If this pays off, it strengthens the chances of a pragmatic Brexit,” said the Conservative minister, who spoke to POLITICO on the basis of anonymity. “When the hardliners come along and say you can’t do this or you can’t do that she can just say, ‘F*** off, I’ve got the mandate’ and there’s nothing they can do.”

Game-changer

This was certainly how it was received by well-informed City analysts.

Rupert Harrison, George Osborne’s former chief of staff who now works for the global asset management company Blackrock, said the move was designed to give May more room for maneuver at home, not abroad, “which is why the pound is rising.” The chances of the U.K. crashing out of the EU with no deal have gone down, he said.

However, he warned pro-Europeans not to go overboard. Brexit was still going to be hard — the landing might just be a little softer.

“To be clear,” Harrison wrote, “this doesn't mean 'soft' Brexit.” May still wants to pull out of the single market, the customs union and the jurisdiction of the European Court of Justice. But if she wins the election she buys herself more time to agree a transition period on the road to a wide-ranging free-trade agreement.

In an analysis shared with its investors on Tuesday afternoon, financial giant Deutsche Bank was even more bullish. “This morning's announcement from PM May of a snap general election on the 8th June is in our view a game-changer for both the U.K.'s Brexit negotiations and sterling,” wrote Deutsche analysts Oliver Harvey and George Saravelos.

The bank said a larger Tory majority gave May the room to agree compromises with the EU and, crucially, a “lengthy transition."

In a bid to calm concerns abroad, May rang a number of foreign leaders to explain her decision. “The PM made separate calls to President Trump, Chancellor Merkel, President Tusk of the European Council, President Juncker of the European Commission and Taoiseach Enda Kenny,” said a Downing Street spokesperson.