He said their success had turned nationalised industries that used to cost the taxpayer pounds 50m a week into companies that generated weekly tax revenues of pounds 60m for the Exchequer.
"That is diminishing the burden on taxpayers, and it helps to pay for health and education," Mr Lang added.
"Nobody can justify unwarranted gain, be it in share options or salary, or whatever," he said. But he then added quite clearly that the privatised utility bosses deserved their gains - with an uncompromising free-market justification for the bonanza pay and perks that have followed privatisation.
"Companies which were inefficient, unproductive, under-invested, in the public sector are now transformed," he said. "And the reason that those individuals who steered them from their inefficient state control to their new success in private ownership, the reason they are doing so well out of it is that they have so dramatically raised the productivity, performances and the profitability of their companies that the stock markets raised the value of their shares."
Mr Lang, whose political profile has been deliberately raised by the Prime Minister - giving him lead responsibility for industrial relations and the minimum wage at the expense of Gillian Shephard, Secretary of State for Education and Employment - is increasingly seen as a middle- ground contender for an eventual succession to John Major. Certainly, his low profile and his non-alignment with the Euro-sceptic right and the Heathite left, could help.
Told he was seen as a future leader, Mr Lang said: "Along with about 300 others. My ambition is confined to doing the job in hand as well as I can, to seeing my party continuing to prosper and to remain in government."
As for the job in hand, with industrial relations and the minimum wage as prime targets for election campaign attacks on Labour, Mr Lang said action would be taken on public-utility strikes and a minimum wage would cost a million jobs.
He said he would not tolerate the public being "held to ransom" by striking public-service workers. The number of days lost through strikes was a 20th of what it was in the Seventies, but he said: "There are still those areas where we see this ugly echo of Seventies trade-union man coming through, and we are developing ways to address them."
The minimum wage, he said, was an easy clap line at a Labour conference and it would make everybody feel better for a day and a half. But he added: "You then have thousands of jobs disappearing from the workforce, particularly at the low-paid, and unskilled and young end of the workforce.
"That is why, if you look at the unemployment rates among young people in France, Spain, Belgium, you find they are dramatically higher than they are in this country."
Asked whether it was right that the taxpayers should have to pay more than pounds 4bn a year subsidising low-pay employers - through income support for their workers - Mr Lang said: "It would cost the taxpayers a hell of a lot more if they have to pay unemployment benefit to a million more people."
Mr Lang's attack on Labour extended to educational standards. After 17 years in office, he said: "Any Conservative government prosecuting its education policies has to fight through the morass of Labour-controlled authorities." It was Tony Blair, he said, who had thus "made a mess of it". However, he conceded that Conservative change in education "hasn't yet delivered results".
There had been a dramatic increase in the number of students going into higher education, and in the numbers getting good A-level grades. "For good pupils, education standards have been rising." But he added: "There remain areas of attention. Gillian Shephard, I know, is looking very closely at the kind of issues that can build on what we have done; more classroom teaching, to get more focus on the fundamentals."
As The Independent revealed last month, Mrs Shephard is expected to announce an enhanced workfare programme at this week's Conservative Party conference in Bournemouth, and Mr Lang will offer his full support.
Workfare had "a part to play" in tackling unemployment, he said. "What is important is that the social security system should not be designed to maintain people in supported isolation but should find routes back in employment, into productive, self-sustaining activity as quickly as possible."Reuse content