David Cameron insisted his Government had "resolve, strength and grit" as he defended a string of enforced U-turns on tax measures.

The Prime Minister said it took courage for an administration to admit it was "ploughing into the brick wall" and change course on high-profile policies.

On Thursday, Chancellor George Osborne bowed to intense pressure to cap tax relief on charitable donations - his third Budget about-face in less than a week.

The switch came hot on the heels of fundamental changes to levies on pasties and caravans announced in March's financial package.

Since taking power in May 2010, the Tory/Liberal Democrat power-sharing coalition has made at least 21 prominent climbdowns - with critics putting the figure far higher.

Labour said the Budget had become an "embarrassing shambles".

But while he acknowledged the "difficulties" thrown up by the Budget, Mr Cameron sought to make a virtue of the Government's willingness to accept its mistakes.

"We've taken difficult decisions on the deficit which we've cut by a quarter in two years, difficult decisions on public sector pay, reforming public sector pensions, standing up to public sector strikes," he told BBC1's Andrew Marr Show.

"Nobody thinks this Government lacks resolve, strength and grit.

"It has all of those things and it also has the courage to say 'Look, if we've got something wrong, let's change it; let's not keep ploughing into the brick wall'."

He added: "There have been difficulties in the Budget and we've had to make some changes.

"When you've got something wrong, there are two things you can do in government: you can plough on regardless, or you can say 'No, we're going to listen, we're going to change it, we're going to get it right'. And that's what we've done and I think that's the right thing to do."

The measures "at the heart of the Budget" remained in place, he said - lifting the threshold at which people start to pay income tax and cutting the top rate of tax from 50p to 45p.

Shadow treasury minister Chris Leslie said: "How can David Cameron claim to be listening when 'ploughing into the brick wall' is exactly what he and George Osborne have done with our economy?

"Despite the chaotic u-turns of recent days, there is no change of heart on the major mistakes George Osborne and David Cameron have made.

"We are in recession with over a million young unemployed thanks to George Osborne's failed plan, which is seeing us borrow £150 billion more than planned. We desperately need a change of course on the economy.

"Yet still the Government will not give the country a real plan for growth and jobs.

"And there is no sign of any regret for a tax cut for millionaires at a time when families with children are being hit by an average of £511 a year this year alone."

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