Britain's cavernous £50 billion investment gap was laid bare by the TUC yesterday as Tory Chancellor George Osborne issued his latest series of throwaway pledges.

Mr Osborne promised to get "Britain building" with plans for 15,000 homes in a new garden city near Ebbsfleet in Kent.

He also unveiled a £6bnboost to his help to buy scheme on BBC1's Andrew Marr show before delivering his latest cuts budget in Parliament on Wednesday.

"This means more homes, this means more aspiration for families, this means economic security and economic resilience because Britain has got to get building," he said.

But doubt was cast on Mr Osborne's latest pledge by TUC research which shows he has failed to deliver previous investment promises.

It shows both public and private investment has fallen since the Tories took power in 2010 and the only growth is in the gulf between planned and actual investment.

Researchers laid blame on inadequate capital spending, which has been slashed by half under the Tories, and cuts to corporation tax have failed to spur business investment.

TUC general secretary Frances O'Grady told Mr Osborne to start making good after years of "ineffective initiative."

"The Chancellor promised to address this failure but instead has presided over a growing investment gap that has held back growth and which risks causing permanent economic damage," she said.

"George Osborne can start to undo the damage caused by slashing capital spending by giving greater financial guarantees to infrastructure projects.

"This should encourage firms to crack on with the construction of much-needed homes, schools and transport routes."

Ms O'Grady also warned the government that planned tax cuts for Britain's lowest paid people would barely help their budgets.

Proposing her alternative, she said: "Damaging welfare cuts are adding to the financial woes of hard-pressed working families and must be reversed.

"The one thing guaranteed to cheer working people would be a bigger salary."

Labour shadow chancellor Ed Balls also labelled Mr Osborne's latest Help to Buy bungs a "damp squib" on BBC 5 Live yesterday - as the Chancellor kept an eye on his child.

"We've got the lowest level of house-building since the '20s," Mr Balls explained.