John McDonnell has ruled out a tough Parliamentary fight to block a ‘hard Brexit’ – insisting Labour will rely on “moral pressure” instead.

The Shadow Chancellor used a speech on the economy to urge his colleagues to be “positive” about the "enormous opportunies" for Brexit and to give up any thoughts of delaying the triggering of the Article 50 notice.

Labour had already rejected calls to hold up Article 50 unless the Government promised a second referendum on the eventual exit deal, insisting it must accept the June referendum result.

But Mr McDonnell went further in his speech ahead of next week’s crucial Autumn Statement, arguing to do so would put Labour on the side of “corporate elites”.

Refusing to accept the reality of the EU exit would also be “leaving the field open to divisive Trump-style politics”.

Mr McDonnell said: “Labour accepts the referendum result as the voice of the majority and we must embrace the enormous opportunities to reshape our country that Brexit has opened for us.

“This means we must not try to re-fight the referendum or push for a second vote and, if Article 50 needs to be triggered in Parliament, Labour will not seek to block or delay it.

“It is time we all were more positive about Brexit.”

Asked how, in that case, Labour would achieve its Brexit aims, Mr McDonnell replied: “I think it’s the moral pressure that we’ll be able to exert right the way across the country.”

The stance was condemned by Caroline Lucas, the Green party’s co-leader, who accused Labour of a “premature capitulation” that would strengthen the Government’s hand.

She said: “We now have less power to persuade the government to give us proper details on their plans ahead of a vote.

“Though we should not seek to overturn the result of the referendum it is down to us as MPs to look closely at the deal on the table before throwing our support behind the government’s plans.”

In the speech, Mr McDonnell also underlined Labour’s commitment to fiscal discipline if it wins power, saying there is “nothing ‘progressive’ about running up big deficits.

He praised Mark Carney, the governor of the Bank of England, and said Labour was committed to protecting the Bank’s independence.

Mr McDonnell also said the previous Chancellor’s cuts had help spark the Brexit vote, saying: “The Tories want you to forget George Osborne but I want to you to remember what he did in detail.

“Because he not only failed on every target he set himself – he plunged Britain’s hard pressed communities into such a state of neglect that they reached for the option of a break with Europe.”

He insisted Labour wanted to keep full, tariff-free access to the single market – even if it would not fight tooth-and-nail for it in Parliament.

“This is the best way to protect jobs and living standards here, Mr McDonnell said.