"In essence, the switch could shift as many as 250 potential plays from Granderson to Gardner, which alone justifies the move, " Spratt said.

WSJ: In the Center of Yankee Change

Ministers say it marks the beginning of a fundamental cultural shift in the welfare system, but critics have raised concerns about the computer system and the switch to a single monthly payment.

BBC: IDS: Universal credit 'simpler and quicker'

The shift from Windows came after IBM's chief information officer Bob Greenberg last autumn challenged employees to make the switch.

BBC: NEWS | Business | HP to sell Linux-based computers