Labour was quick to try to tear holes in George Osborne’s Budget, but the political impact was clear.

Conservative MPs were delighted, while Labour MPs were quiet as acting leader Harriet Harman delivered her statement to the Commons in response to the Chancellor’s triumphant speech.

The days when Budget announcements were wrapped in secrecy are long gone, and many of his measures had been trailed well in advance.

These included cutting tax credits, lowering the benefits cap to £20,000 outside London and increasing the income tax threshold - effectively cutting income tax for many working people.

But Chancellors like to keep a rabbit in the hat to pull out at the end of their statement, and George Osborne had a kept a giant one.

He was giving Britain a pay rise, he said.

A new “National Living Wage” would be introduced for people aged over 25, coming in at £7.20 in April and rising to £9 to 2020.

Documents published by the Treasury explain what this means.

The living wage will actually be a 50p premium added to the minimum wage. While the highest rate of the minimum wage comes into effect once workers are 21, the extra premium applies to those aged 25 or more.

Strictly speaking, the Chancellor can’t guarantee that the living wage will reach £9, as the documents make clear.

The Low Pay Commission will continue to set the minimum wage as it does now. But the Government wants the minimum wage to reach 60 per cent of median earnings by 2020, and it predicts that the minimum wage and living wage premium combined will reach £9 by 2020.

The move is part of the Chancellor’s continued campaign to prove that the Conservatives, rather than Labour, are the party of working people - and that they want to help working people on modest incomes, not just the rich.

It also goes some way to offsetting criticism that cuts to tax credits penalise exactly the people that the Conservatives say they want to help.

There’s one snag, which is that what the Government is proposing is not actually a living wage.

The phrase “living wage” has so far been used to refer to a sum which academics calculate people need to earn in order to enjoy a reasonable standard of living.

It’s not compulsory. Firms are free to pay less (as long as they pay the minimum wage, currently £6.50 an hour for people aged 21 and over, of course).

But many MPs, including Tories such as Boris Johnson as well as Labour MPs, have been campaigning to encourage firms to pay it.

And a number of local authorities have also declared themselves living wage employers.

The trouble is that the living wage is currently £7.85 an hour outside London, and £9.15 an hour in London.

So George Osborne’s “compulsory living wage” is actually lower than the living wage everyone has been talking about until now.

This may be an example of Mr Osborne being too clever for his own good. After all, he could simply have announced he was increasing the minimum wage by 50p and let people judge the policy on its merits.

Instead, he chose to co-opt the idea of a living wage, and open the door for Labour and other critics to say his announcement was less impressive than it appears.

Nonetheless, Mr Osborne can claim that “Britain is getting a pay rise”, as he triumphantly proclaimed in his Budget statement.

The Treasury thinks 2.7 million will see their pay increase because they are directly affected.

And the Office for Budget Responsibility, the watchdog set up by the Treasury, calculates that another 3.25 million people will also see an increase in their wages, as increasing pay at the bottom of the pay scale will also lead firms to increase wages for staff who are slightly higher up.

The Chancellor can claim that he has beaten Labour’s election pledge. Labour’s manifesto in May promised: “We will improve the security and reward of working life by raising the National Minimum Wage to more than £8 an hour by October 2019.”

His figures (like Labour’s) are not adjusted for inflation - so we’re talking £9 an hour in today’s money, which will be more like £8 an hour by 2020.

But it’s still an increase - which is actually highlighted by his admission that the policy is expected to cost 60,000 jobs.

Will it make up for the Chancellor’s cuts to tax credits?

It’s possible some people will be worse off, because the Chancellor is freezing working age benefits for four years, and limiting the support provided through tax credits to a maximum of two children.

But one bizarre consequence is that some of the biggest gainers will be wealthier households.

The Office for Budget Responsibility points out that “many workers on the national living wage will be households’ second earners” - so about half the extra money going into pockets will go to households which are already in the top 50 per cent in terms of income.