Keir Starmer today hit back at criticism of his holiday in Mallorca - saying: "I'm not going to apologise".
The Labour leader had taken a break with his wife Victoria and two children on the Spanish island - returning to airwaves last Friday.
By then, Gordon Brown and the Lib Dems had both called for the price cap on energy bills to be frozen ahead of a predicted hike to £3,600 in October and £4,200 in January.
Labour's leader today announced his own £29bn plan to freeze bills at their current level of £1,971 a year until March 31 next year, and refused to rule out spending more later on.
But he insisted his holiday had not got in the way of the plan being announced, as officials began drawing it up in July.
He told BBC Breakfast: "I’ve got a very important job as leader of the Labour Party, as leader of the opposition.
"But I’ve also got another job that’s really important and that is I’m a dad.
"And I’m not going to apologise for going on holiday with my wife and kids.
"It’s the first time we’ve had a real holiday for about three years."
Labour's leader said the delay was due to the need for his plan to be "fully costed" and "comprehensive" - and to be based on reliable forecasts, the latest of which came out last week.
He dismissed controversy over the time it took him to make today's announcement.
He told ITV's Good Morning Britain: “For millions of people who are really anxious about what’s going to happen in the autumn they’re not going to start asking about who said what, when in the last week.”
Pundits had compared his situation to Boris Johnson, who took a honeymoon in Slovenia, returned for a few days and went to a cost-of-living meeting with energy firms, and then jetted off again to Greece.
But Sir Keir told the Mirror "of course I was" having meetings on holiday, adding: "That's the nature of the beast. And that's not just this holiday, that's every time I go away.
“But we've been actually working on it for for a long time. We needed all the forecasts - the credible ones didn't come out until the middle of last week - to be sure exactly what the costings would be.”
He added: “We have been working on this package for weeks because it became obvious months ago that we were going to have a national emergency this autumn.
“And I spent a lot of last winter talking to people who were hugely impacted by the situation then.
“In Dewsbury I spoke to an 84-year-old pensioner with mobility issues who told me she was too scared to put the central heating on. Other pensioners who said they were sitting in blankets all day.
“So the intensity of the problem has been there for a very long time, which impacted on me.”
Labour today pledges it would freeze the energy price cap at its current £1,971 until the end of March next year.
That would block rises to £3,600 in October and £4,200 in January. The £29bn difference would be given to energy firms and not paid back.
Some 75% of voters back fixing the cap on bills, even if it means more government borrowing, according to a YouGov poll for The Times.
Speaking to the Mirror, Labour’s leader did not rule out having to spend more from April - when bills could top £5,000.
IFS director Paul Johnson said he could have to spend another £30bn to make the policy last 12 months.
Labour would raise £14bn of the £29bn by axing the £400 discount off energy bills from October - claiming it’s not needed if bills are frozen.
Another £8bn would come from the Tories’ windfall tax on oil and gas producers. Labour would backdate it to January and axe an “absurd loophole” that lets firms claim tax relief on 91% of reinvested profits.
The last £7bn would come due to the freeze itself lowering the peak of inflation from 13% to 9% - slashing debt interest payments, Labour claimed.
But Keir Starmer rejected calls to nationalise the big energy firms - long called for by many on the left.
He told BBC Breakfast: “The choice we’ve made in our plan is every single penny that’s needed for this plan will go directly to reducing the bills of families up and down the country.
"If you go down the nationalisation route, then money has to be spent on compensating shareholders.
"And I think in an emergency like this, a national emergency where people are struggling to pay their bills, I think the right choice is for every single penny to go to reducing those bills."
