Peter Mandelson has attacked Labour’s left-wing economic programme as “lots of free offers” that will fail to transform the country – but admitted it could work with voters.

In a pamphlet, the New Labour founder criticised John McDonnell, the shadow chancellor, for “simply telling the movement what they want to hear”, rather than offering “new ideas”.

Lord Mandelson warned that power taken from “globalised capitalism” would be handed to “ill-equipped civil servants and a new generation of trade union barons” – instead of to citizens.

And he accused Mr McDonnell of “positioning Labour against Tony Blair”, rather than offering a programme to rival Clement Attlee’s post-war government for its radicalism.

However, Mr Blair’s former close ally also acknowledged Labour could yet win power with its left-wing manifesto – but only if it dumped the unpopular Jeremy Corbyn.

“Were it not for Jeremy Corbyn’s extremely poor personal ratings – they make a majority Labour government an impossibility while he remains – Labour’s prospects would be far stronger than the party’s detractors imagine,” Lord Mandelson wrote.

“There are few if any of Labour’s flagship policies that do not score good opinion poll ratings – until Corbyn is identified as their author.”

Writing for the centre-right Policy Exchange think tank, he argued Boris Johnson’s rejection of austerity would “make it harder for the Conservatives to attack McDonnellomics in the coming election”.

Both parties would be competing for “economic worriers who favour security, law and order”.

Brexit and climate protests at Labour party conference: In pictures Show all 12 1 /12 Brexit and climate protests at Labour party conference: In pictures Brexit and climate protests at Labour party conference: In pictures Labour leader Jeremy Corbyn walks past anti-Brexit campaigner on the second day of the party conference in Brighton AFP/Getty Brexit and climate protests at Labour party conference: In pictures A protester holds a sign mocking Labour leader Jeremy Corbyn's Brexit stance at the party conference in Brighton EPA Brexit and climate protests at Labour party conference: In pictures Activists from anti-climate change movement Extinction Rebellion march on the Labour conference in Brighton AFP/Getty Brexit and climate protests at Labour party conference: In pictures Delegates take part in an informal vote on Labour's Brexitr stance at the party conference in Brighton AFP/Getty Brexit and climate protests at Labour party conference: In pictures Shadow foreign secretary Emily Thornberry leads a march in support of a second referendum on Brexit Getty Brexit and climate protests at Labour party conference: In pictures Anti-Brexit protesters take part in a People's Vote rally during the Labour party conference in Brighton EPA Brexit and climate protests at Labour party conference: In pictures Extinction RebelliActivists from anti-climate change movement Extinction Rebellion march on the Labour conference in Brightonon EPA Brexit and climate protests at Labour party conference: In pictures Extinction Rebellion activists march on the Labour conference in Brighton AFP/Getty Brexit and climate protests at Labour party conference: In pictures A delegate arrives carrying a briefing from the Labour Representation Committee to the Labour party conference in Brighton Getty Brexit and climate protests at Labour party conference: In pictures Prominent anti-Brexit campaigner Steve Bray protests on Brighton beach during the Labour party conference Reuters Brexit and climate protests at Labour party conference: In pictures Anti-Brexit protesters take part in a People's Vote rally during the Labour party conference in Brighton EPA Brexit and climate protests at Labour party conference: In pictures Activists raise a banner calling for the Labour party to restore the original Clause 4 of its constitution, which would pledge the party to nationalising all industry Getty

“Brexit has skewed them towards the Conservatives but, if you remove this factor, they share many Labour instincts and are drawn to many of the ‘populist’ elements of Labour’s ‘re-balancing’ agenda,” Lord Mandelson said.

“These voters back higher spending on healthcare, education, policing and defence, which is why the Conservatives, while condemning Labour’s tax and spend policies, are nonetheless turning on spending taps of their own.”

The verdict comes in a pamphlet entitled McDonnellomics: How Labour’s economic agenda would transform the UK, which argues Labour would deliver the “biggest shift in UK economic policy since the advent of Thatcherism”.

The party is pledging to hike taxes on corporations and the highest earners, introduce a financial services tax to tame the City of London and hand 10 per cent of every company’s shares to its workers.

As well as overturning austerity, Labour would abolish tuition fees, provide free prescriptions and social care and nationalise the railways and utilities.

But Lord Mandelson said: “Instead of moving Britain forward, with new ideas and utilising the opportunities that digital technology and AI, for example, offer us to transform the economy and public services, a Corbyn-McDonnell government wants to reassert the statist mindset that New Labour disavowed.”