Liz Truss's short-lived government "blew it" during its time in charge of the country, her former chancellor Kwasi Kwarteng has said.
Mr Kwarteng said Ms Truss's seven weeks in Downing Street, which culminated in her loss of complete political authority and resignation, saw her top team get "carried away".
Reflecting on the sweeping tax cuts and economic reforms he unveiled as part of the mini-Budget, Mr Kwarteng told the Financial Times: "It was very exciting, you felt you were part of a project."
But the measures, announced just two weeks after the multi-billion energy support package, would go on to spook the markets and saw the pound sink to its lowest level in 37 years.
The former chancellor soon U-turned on his flagship policy of abolishing the 45p top rate of tax and was eventually sacked by Ms Truss on October 14. Jeremy Hunt, his successor, would go on to rip up the majority of his agenda.
"People got carried away, myself included," Mr Kwarteng said. "There was no tactical subtlety whatsoever.
"My biggest regret is we weren’t tactically astute and we were too impatient. There was a brief moment and the people in charge, myself included, blew it."
Mr Kwarteng took a defiant stance at the time by doubling down on the £45 billion of tax cuts in the mini-Budget, adding: "There's more to come."
Following his reversal on the top rate of tax, he promised to publish a "credible" plan to get debt falling and insisted "I'm not going anywhere" on the day before his sacking.
He had flown back early from a visit to the International Monetary Fund (IMF) in America to be told by Ms Truss that he was on the way out amid growing economic and political uncertainty.
Told by the then-Prime Minister "you're going to have to go", the Financial Times reported Mr Kwarteng replied: "I know. I've seen it on Twitter."
Mr Kwarteng appeared to blame Ms Truss last month in his first public remarks since he left No 11.
During an interview with Talk TV, he said: "I said we should slow down… I said: ‘You will have two months if you carry on like this.'"
Jacob Rees-Mogg, Ms Truss's former business secretary who has long been a supporter of small-state conservatism, said on Friday the failure of her government came as a "big setback".
"We now have the highest taxes for 70 years, and there is no challenge to that.
"There’s a long way to go for people with my beliefs to win this argument."
Mark Littlewood, the director-general of the Institute of Economic Affairs (IEA) think tank which influenced many of Ms Truss's ideas, acknowledged the chaos of her time in power but insisted the broader vision underpinning her premiership was sound.
"You might have the recipe for making the most perfect and delicious pizza, but if the chef is hubristic, or crazy, or incompetent, you are not going to end up with a particularly tasty pizza," he said.
"Does that mean you shouldn’t eat pizza again? No, it just means you shouldn’t eat pizza cooked by that chef."
It came as the Financial Times appeared to hint at a prospective political comeback by Ms Truss, who this week confirmed she would stand again as an MP at the next election.
While she was reported to have initially felt "very low" after her departure from No 10, she is said to have told allies: "I lost a battle, but I haven't lost the war."