Hillary Clinton didn't prepare a concession speech during the US presidential election because she was convinced she would not lose, the former Secretary of State has admitted.

“I had not prepared a concession piece because I really thought I was going to win,” Ms Clinton said on BBC’s The One Show. “So when it became clear I was going to lose the electoral college ... I had to come up with something to say.”

She added: “When it was over, I got into the car with my husband and I just felt like the plug was pulled. Every ounce of energy and adrenaline was just gone.”

But the former Secretary was not alone in her lack of preparation. Few people in American politics or media had predicted Ms Clinton’s loss – Politico even called it “the biggest upset in US history”.

In fact, Ms Clinton said even Donald Trump sounded shocked when she called him to concede the next day.

“He was as surprised as I was,” she said.

In pictures: Protests, pomp and Donald Trump Show all 30 1 /30 In pictures: Protests, pomp and Donald Trump In pictures: Protests, pomp and Donald Trump President-elect Donald Trump acknowledges guests as he arrives on the platform at the US Capitol in Washington DC Getty Images In pictures: Protests, pomp and Donald Trump Donald Trump is sworn in as the 45th president of the United States by Chief Justice John Roberts as Melania Trump looks on during the 58th Presidential Inauguration at the U.S. Capitol in Washington AP In pictures: Protests, pomp and Donald Trump President Donald Trump shakes hands with Justice John Roberts after taking the oath at inauguration ceremonies swearing in Trump as the 45th president of the United States Reuters In pictures: Protests, pomp and Donald Trump President Donald Trump raises his fists after his inauguration on the West Front of the U.S. Capitol Getty In pictures: Protests, pomp and Donald Trump U.S. President-elect Donald Trump greets outgoing President Barack Obama before Trump is inaugurated during ceremonies on the Capitol in Washington Reuters In pictures: Protests, pomp and Donald Trump resident-elect Donald Trump arrives on the platform of the US Capitol in Washington DC Getty Images In pictures: Protests, pomp and Donald Trump Attendees partake in the inauguration ceremonies to swear in Donald Trump as the 45th president of the United States at the U.S. Capitol in Washington DC Reuters In pictures: Protests, pomp and Donald Trump US President Donald Trump delivers his inaugural address during ceremonies at the US Capitol in Washington DC Getty In pictures: Protests, pomp and Donald Trump U.S. President Donald Trump waves with wife Melania during the Inaugural Parade in Washington DC Reuters In pictures: Protests, pomp and Donald Trump Protesters registered their rage against the new president Friday in a chaotic confrontation with police who used pepper spray and stun grenades in a melee just blocks from Donald Trump's inaugural parade route. Scores were arrested for trashing property and attacking officers AP In pictures: Protests, pomp and Donald Trump Demonstrators protest against US President Donald Trump in Washington DC Getty Images In pictures: Protests, pomp and Donald Trump A woman holds a sign before the start of the Presidential Inauguration of Donald Trump at Freedom Plaza in Washington DC Getty Images In pictures: Protests, pomp and Donald Trump Anti-Trump protesters prepare banners for a protest against the inauguration of US President-elect Donald Trump, in Berlin REUTERS In pictures: Protests, pomp and Donald Trump Demonstrators shout slogans against US President-elect Donald Trump in Washington DC Getty Images In pictures: Protests, pomp and Donald Trump Demonstrators march, block foot traffic and clash with U.S. Capitol Police at the entry checkpoints for the Inauguration of Donald Trump Alamy Live News In pictures: Protests, pomp and Donald Trump Demonstrators display a banner as people arrive for US President-elect Donald Trump's inauguration in Washington DC Getty Images In pictures: Protests, pomp and Donald Trump A man displays a placard as people lineup to get into the National Mall for the inauguration of US President-elect Donald Trump in Washington DC Getty Images In pictures: Protests, pomp and Donald Trump Protesters demonstrating against U.S. President Donald Trump raise their hands as they are surrounded by police on the sidelines of the inauguration in Washington DC Reuters In pictures: Protests, pomp and Donald Trump A demonstrator wearing a mask depicting Donald Trump protests outside the US Embassy in London Getty Images In pictures: Protests, pomp and Donald Trump Demonstrators hold placards as they protest outside the US Embassy in London Getty Images In pictures: Protests, pomp and Donald Trump Former US President George W. Bush and First Lady Laura Bush arrive for the Presidential Inauguration at the US Capitol Rex In pictures: Protests, pomp and Donald Trump Michelle Obama and Dr. Jill Biden share an umbrella as President Donald Trump delivers his inaugural address at the inauguration in Washington DC Rex In pictures: Protests, pomp and Donald Trump Former Democratic presidential nominee Hillary Clinton and former President Bill Clinton arrive on the West Front of the U.S. Capitol in Washington Reuters In pictures: Protests, pomp and Donald Trump U.S. Vice President Mike Pence takes the oath of office on the West Front of the U.S. Capitol in Washington, DC Getty Images In pictures: Protests, pomp and Donald Trump Advisors to President-elect Donald Trump, Kellyanne Conway and Steve Bannon depart from services at St. John's Church during the Presidential Inauguration in Washington Reuters In pictures: Protests, pomp and Donald Trump Protesters demonstrating against U.S. President Donald Trump take cover as they are hit by pepper spray by police on the sidelines of the inauguration in Washington DC Reuters In pictures: Protests, pomp and Donald Trump An activist demonstrating against U.S. President Donald Trump is helped after being hit by pepper spray on the sidelines of the inauguration in Washington DC Reuters In pictures: Protests, pomp and Donald Trump A police officer tries to tackle a protester demonstrating against U.S. President Donald Trump Reuters/Adrees Latif In pictures: Protests, pomp and Donald Trump Police arrest and detain a protester in the street in Washington DC Rex In pictures: Protests, pomp and Donald Trump A police officer falls to the ground as another shoots pepper spray at protesters demonstrating against U.S. President Donald Trump on the sidelines of the inauguration in Washington DC Reuters

Ms Clinton appeared on The One Show to promote her recently released book, What Happened. The book details the 2016 presidential election and its aftermath – including moments like the one Ms Clinton described on Friday.

During the interview, Ms Clinton said the book was a story not just about the election, but also about resilience.

“Everybody has to bounce back from something,” she said. “...And anything that I could say that might give some hope and some courage to anyone else who is facing their own disappointments would be wonderful.”

Ms Clinton’s said her preferred coping mechanisms were sweatpants, chardonnay, and long walks in the woods. She also sung the praises of “alternate nostril breathing” – a relaxation tactic she discusses at length in the book.

Hillary Clinton: Trump is the most dangerous president the US has ever had

But Ms Clinton and the TV hosts also discussed more serious issues, like the lack of women in politics in the US.

“When you’re a woman who steps out and says, ‘I want to lead in our country,’ that raises a lot of questions,” said Ms Clinton, who dedicated several section of her book to the effects of sexism on women in power.

“We are behind in the United States, and I’m hoping – having gotten the nomination of one of our two major parties – that I've pushed that door open a lot more, so that hopefully we can see a woman president in my lifetime," she said.