BRITAIN is to have a new generation of nuclear submarines and missiles after a promise by Gordon Brown yesterday to replace the Trident deterrent if and when he becomes Prime Minister.

The Chancellor, widely expected to take over from Tony Blair next year, faced a furious response from the Left after pledging to retain the nuclear capability in this Parliament and “in the long-term”. But the Chancellor was told that he was upsetting his natural allies in the party and the unions after using a City speech to make his most important non-economic policy pledge so far.

In remarks that will please the the Armed Forces and the US Government, Mr Brown was trying to show that, as Labour leader, he would not lurch to the Left or be soft on defence.

A decision will be needed during this Parliament if Trident is to be maintained beyond its lifespan. Ministers are expected to take that decision early next year and Mr Brown was giving his first public confirmation that he would sign up to a full replacement for Trident if that was the advice of Britain’s military commanders.

That could cost between £12 billion and £15 billion, on recent estimates. The Government is looking at a number of options and assessing the expense. The most likely replacement is another submarine-launched weapon. Both the existing Vanguard Class submarines and the 7,500-mile-range Trident D5 missiles they carry could have their service life extended, under one option being examined.

Paul Murphy, the chairman of the Parliamentary Intelligence and Security Committee, welcomed Mr Brown’s commitment. “Protecting national security is the first duty of any government, and this responsibility will be safe in Gordon Brown’s hands.”

But there was anger on the Left as news of Mr Brown’s speech began to emerge. Gordon Prentice, Labour MP for Pendle, told The Times that Mr Brown’s statement, made in his annual Mansion House address, defied belief. “How can we ask other countries like Iran not to become nuclear weapon states when we are not only not getting rid of our weapons but replacing and enhancing them?” he said.

“This seems to be part of Gordon cementing the Blair legacy. He is saying all sorts of things to show there is no difference between the Blair and Brown agendas.

“But he is jeopardising the support he might have been expected to take for granted — not just in the unions but among MPs and the constituency parties. This is very disappointing indeed. Many MPs will be looking for a candidate who gives the clearest commitment to non-proliferation of nuclear weapons.”

The Conservatives said that Mr Brown was doing no more than repeating Labour’s manifesto pledge to keep the deterrent during this Parliament. But Treasury sources replied that the speech committed Mr Brown to keeping it beyond the present Parliament. That meant signing up to a decision to replace or update it.

Mr Brown’s declaration is his clearest warning yet to the Left that he will not reverse Blairite policy positions. In the same speech he said that public sector reform would be “stepped up, broadened, deepened and intensified”.

On national security he would make “the right long-term decisions”. He promised to show the “same strength of purpose we will demonstrate in protecting our security in this Parliament and the long term — strong in defence in fighting terrorism, upholding Nato, supporting our Armed Forces at home and abroad, and retaining our independent nuclear deterrent”.

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