British politics risks an unprecedented shift to the far right as a result of public disillusionment if a Labour government fails to enact radical change, the former shadow chancellor John McDonnell has warned. Writing in the Guardian, McDonnell said the threat would come not just from Nigel Farage’s resurgent Reform UK but from the return of a Conservative party “shorn” of its moderate wing and dominated by populists. McDonnell, who served in the shadow cabinet under Jeremy Corbyn, reflected the views of others on his party’s left who are impatient with what they regard as Labour’s too-cautious approach. “The central messaging of Keir Starmer’s electoral strategy is that he’s not Jeremy Corbyn and that Labour is not the disaster that is the Conservative party,” he said. McDonnell pointed to the polling figures of Reform UK, reaching as high as 11%, as evidence of “how a far-right populist programme can pull the major parties on to a rightwing agenda”. It was Farage, Reform’s honorary president and the focus of speculation about a possible return to frontline politics, who had “polluted” Britain’s politics during the year of the referendum on the UK’s membership of the EU, McDonnell added. But he claimed that the “more significant danger” from the far right would emerge if voters who placed their faith in Labour did not see change. “People will be patient as they fully realise how broken Britain is, but the foundations of credible and radical change will have to be seen to be being laid early in the life of the incoming Labour government,” he writes, calling for a “real strategy” to restore the value of wages and incomes. There had also been a retreat on key core policy commitments, he said, such as the level of investment needed for Labour’s green new deal. “If Labour fails to set out early upon a path of radical change to secure the all-round wellbeing and security of our people, then inevitably disillusionment will set in,” McDonnell said. “The risk then is the potential for a significant shift in our politics to the right, with the return of a Conservative party completely shorn of any traditional one nation Tories and under the dominance of the populist right both within the party and beyond.” Farage has continued to keep people guessing about his intentions of a return to politics, which could involve coming back as the leader of Reform or joining the Conservatives. Reform’s leader, Richard Tice, told a press conference on Wednesday that terrified Conservative MPs were pleading with the party not to stand against them in the general election and that Farage was “committed” to aiding his party’s efforts. While the surge in support for Reform is regarded as presenting a major threat to Conservative electoral hopes by dividing the vote on the right in many constituencies, YouGov polling last year found that voters who supported the Tories in 2019 were more likely to switch to Reform than to Labour. A Labour spokesperson said: “With Keir Starmer’s leadership, the Labour party has changed and is unrecognisable to the party which was rejected by voters in 2019. Our five bold missions will spark a decade of national renewal, to make working people better off and give Britain its future back.”