Corbyn warned against mass nationalisation as key plank of the party’s constitution comes under review

Tony Blair’s change to the Labour constitution in 1995 was seen as key to his New Labour project

Labour has begun the process of reversing Tony Blair’s reform of Clause 4, the totemic section of the party’s constitution.

Mr Blair ditched the old statement of his party’s aims and values, regarded as a commitment to widespread nationalisation, in 1995. The decision was viewed as a significant moment in the party’s history.

Labour’s national executive committee (NEC), controlled by supporters of Jeremy Corbyn, agreed on Tuesday to set up a working group to examine changing the document.

The development comes as a new poll shows that the Liberal Democrats have overtaken Labour after Jo Swinson promised to halt Brexit without a referendum.

Mr Corbyn and his allies have been warned against reverting to the original 1917 wording of the party’s constitution, which committed Labour to “secure for the workers by hand or by brain the full fruits of their industry” on the basis of “common ownership of the means of production, distribution and exchange”.

This was replaced by Mr Blair with support for “a dynamic economy, serving the public interest, in which the enterprise of the market and the rigour of competition are joined with the forces of partnership and co-operation to produce the wealth the nation needs”.

Alan Johnson, the former home secretary who was the only trade union leader to back Mr Blair’s changes, warned that a return to the old version would mark the Labour left’s “final triumph over Blairism”. He told The Times that though he did not object to updating the wording it must not revert to the original.

“The version so dearly beloved by Corbyn and his doctrinaire chums was a product of 1917 and committed the party to the public ownership of everything,” Mr Johnson said. “The word ‘socialism’ wasn’t in it. Neither were important issues such as women’s ights even mentioned. I suspect Momentum will want to go back to the old wording, which they’d see as their final triumph over Blairism. Except of course that nothing can erase our three election victories or the enormous good that the Blair and Brown governments did in the causes of eradicating poverty and of greater equality.”

When Mr Corbyn was campaigning for the Labour leadership in 2015 he appeared open to reversing Mr Blair’s changes to Clause 4, saying: “I think we should talk about what the objectives of the party are, whether that’s restoring Clause 4 as it was originally written or it’s a different one. But we shouldn’t shy away from public participation, public investment in industry and public control of the railways.”

Last year John McDonnell, the shadow chancellor, said that the original principles of Clause 4 “are as relevant today as they were back then — fair, democratic, collective solutions to the challenges of the modern economy”.

The move came after Labour members in Dundee submitted a motion to this weekend’s Labour conference calling for “the restoration of the pre-1995” version. The motion said that the old wording offered the route to a “socialist transformation of society”.

The NEC asked them to withdraw the motion in favour of the working group. If they decide against this Clause 4 will be debated and voted on in Brighton this weekend, but the NEC will urge delegates to reject the motion. A Labour source said: “This is jumping the gun. The NEC is asking the proposers to withdraw the motion. If they do not, the NEC will recommend it is opposed.”

A new YouGov poll for The Times puts the Lib Dems on 23 per cent, up four points on last week and ahead of Labour, which is down two points at 21 per cent. It is the first time Labour has been in third place since July. The Conservatives are on 32 per cent, unchanged on a week ago.

Just half of those who backed Labour in the 2017 election are sticking with the party, with a quarter going to the Lib Dems and a further 9 per cent backing the Brexit Party. The boost for the Lib Dems is fuelled by support among Remainers, with 41 per cent of those who voted against Brexit in 2016 backing the party, up eight points in a week.

In his 2010 autobiography, A Journey, Mr Blair said that the old version of Clause 4 “was hallowed text repeated on every occasion by those on the left who wanted no truck with compromise or the fact that modern thinking had left its words intellectually redundant and politically calamitous”.

Wes Streeting, the MP for Ilford North, said: “This obsession with our own rulebook and structures when we are weeks away from a likely general election is the most extraordinary self-indulgence.”

Pat McFadden, a former adviser to Mr Blair and now MP for Wolverhampton South East, said: “The change to Clause 4 was part of the modernisation of the Labour Party that led to three great election victories, the only convincing majorities that we’ve had in the past 50 years. We did it to make clear to the public that we were a party for today and the future.

“If people want to re-examine the words they can do that, but their objective should be for a Clause 4 for today, not to reach for one from a century ago.”