Not so long ago, Fiona Hill was the most powerful woman in Whitehall. She ran Downing Street with an iron grip for the first year of Theresa May’s premiership alongside her co-chief of staff Nick Timothy. Ministers bowed to their authority, civil servants feared them, Tory MPs complained of a power grab by a duo of unelected officials. As the former Labour MP Frank Field put it: ‘People know that Fiona is not someone you mess around with.’ But after the Tories fell short of a majority in the 2017 snap election, she and Timothy were forced to resign. Hill flew to America and disappeared from public life.

We meet in The Spectator’s offices to record an episode of my podcast, Women with Balls. She is bright-eyed and dressed in a red two-piece suit. This is her first interview since leaving Downing Street five years ago, and she tells the story of election night. Some polls had predicted the Tories would win a majority of more than 100 seats. Instead, the tiny majority won by David Cameron in 2015 was lost and there was a hung parliament. Hill recalls how she got the news just before 10 p.m. ‘Andy Marr called me and told me what the exit poll was,’ she says. ‘I felt like I’d been kicked in the stomach. I was aware that I was there in body, but I wasn’t really there at all in my mind.’

May had called the snap election to deliver‘ certainty and stability’ and had ended up with neither. What went wrong? ‘The polls indicated that we would win fairly well,’ she says. ‘Election campaigns are almost like voodoo. You can get [good] luck and you can also get bad luck. It doesn’t matter if you’ve got your messages right.’

Some factors were, however, within the campaign’s control – such as the ‘dementia tax’. May felt so confident of winning that she announced that well-off pensioners ought to pay more for care-home costs. The plan was applauded as brave in The Spectator but Tory MPs were terrified, thinking that elections are only won when the elderly are bribed. Hill was also sceptical.

‘I’d worked with Jeremy Heywood [the cabinet secretary] on it in government,’ she says. ‘I knew that it hadn’t been tested properly – it had only been tested inside the confines of the civil service.’ Like Liz Truss’s 45p tax cut, no one really foresaw that a backlash was coming. ‘If something is complex to understand or to communicate then it means that it hasn’t been tried and tested enough. And I didn’t feel it had been.’

Another sign of the ‘voodoo’ of election bad luck came on a plane journey following the Manchester Arena terrorist bombing. ‘The cockpit window shattered and we had to drop from the sky,’ she says. ‘I hadn’t really been feeling particularly great about the general direction of the campaign anyway. But there was something about that moment that I felt was a bit of an omen.’

Hill, a former journalist at the Scotsman, spent a brief spell in public relations – ‘the worst three months of my life’ – before she joined the Tories as an adviser. She worked with May from her time in opposition through to government – proving indispensable to her at the Home Office in Marsham Street. ‘I absolutely loved that job,’ she says. ‘One of the reasons that I called my [new] consultancy Marsham Street Consultants is because I just loved being there. There’s nothing more intellectually satisfying than working in a risk environment for me. I just completely get off on it.’

Calling a snap election was the biggest risk of all, and she still thinks it was right to take it. ‘It was the only thing to do, because the majority was so slim.’ But the fallout after the result hit her hard. ‘I was forced to resign,’ Hill says. ‘I didn’t personally think that I should be resigning, because I didn’t really feel like I’d done anything massively wrong. Maybe with hindsight I did. Someone else can be the judge of that. But just straightforwardly she called me and said you have to resign, so I resigned.’

She doesn’t blame May for dropping her. ‘She had to keep going. I understand the rules of politics – and life. I understood that I had to be collateral damage. She did the right thing sacking us. Nick was already resigning anyway. As much as I understood all the reasons, for the weeks and months that followed I felt there was a lack of protection around me.’ The papers blamed her for the Tories’ election failures and didn’t hold back. ‘I found that quite hard, even though as a former journalist I know how it works. I know how politics works. Now, of course, I accept it. It’s not a thing anymore, but at the time it was just really horrible.’

She says more protection ought to be in place for those who find themselves in similar situations. ‘For a fairly young woman who lives by herself, to be allowed to be thrown to the wolves like that was potentially not very good. Luckily I’m a strong person. But if I’d been a lesser person I may have thrown myself in the Thames.’ She relied on her family for support: ‘I am exceptionally close to my siblings.’

Things didn’t get much better. In the month after the election, Hill came face to face with someone who had broken into her flat. The break-in, she says, was ‘probably a political thing’. ‘When I screamed, he laughed. These were all the by-products of having your profile raised in that kind of way. I think too often in politics, people forget that actually we are all human beings. Sometimes, you can take the collateral – because you know that that’s the game. But I don’t think that there’s any harm in having some form of safety net.’

That was when she decided to go to America. ‘I went to stay with my poor friend Laura in New York, who had basically three months of me saying, “Laura, how do I turn a computer on?” or “Laura, could you just fix this IT problem?” She was a good friend for putting up with me and my IT limitations.’

Why has she stayed silent? When Nick Timothy left Downing Street he almost immediately became a columnist and re-entered the political debate. ‘I didn’t really feel that I had anything of any consequence to say at that point,’ she says. ‘Also, I’m very discreet and loyal. If I had said anything at that point I’d have only fed the frenzy.’ But five years under the radar? ‘It’s good to go slow when you’re rebuilding, because you want to get the next phase of your life absolutely right,’ she says. ‘And I feel like I’ve got there.’