Tony Blair's former IT chief has said Labour ministers ordered expensive computer projects because they wanted their policies to "sound sexy".
Ian Watmore - who is now in charge of a Whitehall efficiency drive - gave a scathing assessment of the previous government's IT record.
He told the public administration committee Labour's procurement had been over-ambitious and badly-managed.
The coalition has called a halt to big IT projects to save cash.
In a strategy document published by the Cabinet Office, it vowed to move to "smaller more manageable projects" and said no scheme will cost more than £100m.
It has also promised to open up procurement to smaller firms, who have found it difficult in the past to break the grip of giants such as HP, BT and Fujitsu, who together get about a third of central government contracts, worth about £5bn a year.
Mr Watmore, who is permanent secretary at the Cabinet Office, said some of the high profile IT "fiascos" under the previous government had not been down to defective technology but to poor project management and badly-defined policies.
Too often, he told the Commons public administration committee, ministers simply ordered IT as an "after thought... or worse, there were people thinking they needed to have a piece of technology to make their policy sound sexy".
Mr Watmore became the head of Tony Blair's e-Government Unit in 2004 - at the height of Labour's IT procurement strategy - before going on to head the then Prime Minister's Delivery Unit.
He then left government for a brief spell as chief executive of the Football Association, before being brought back to Whitehall last year by Cabinet Office minister Francis Maude - who was also being grilled by the committee - with the task of cutting waste.
But it was Mr Watmore's career before entering government, when he was managing director of IT consultancy giant Accenture, that came under the spotlight most during the two-hour grilling by MPs.
Committee chairman Bernard Jenkin told him: "You come from exactly the large corporate culture which has bedevilled IT procurement in government. Are you part of the cultural change the minister is looking for, or aren't you just part of the problem?"
Mr Watmore replied: "I am certainly not part of the problem and I would contest that the corporate industry of this country has caused the problems."
He said the "so-called IT disasters" of recent years were not down to technical problems but "over-ambitious projects" that were expected to deliver complex changes at a national level on a single day, "the so-called 'Big Bang' implementation".
Mr Jenkin also questioned the government's commitment to "open source" software, asking how many civil servants in charge of making the policy work had a background in the open source community. He pointed out that the previous government's "open source" guru had left to join Microsoft.
Mr Watmore, who claims to have already saved £2bn in Whitehall efficiencies, said he wants to end the UK government's reliance on Microsoft products, which are used by about 90% of civil servants.
He insisted the government was committed to using more "open source" software to save cash - but had to balance this with concerns about how easily it could be "hacked".
His "personal" view, he added, was that Apple products, which he said he used at home, should also be used more in government.
"I personally would like to see people move off Microsoft products onto open source or use Apple technology.
"I use Apple at home. I know it's not very open but I use it. I love it, it works and I think it is great - I'm Steve Jobs' best customer.
"But 95% of the business and government world still use Microsoft for its basic desktop products because it is reliable and it works.
"I think we, in government, have an opportunity to change that game quite dramatically, particularly on desktop technology, by getting greater use of open products."