“Loading ever more taxes on to working people and keeping people working when they deserve to retire in peace is completely the wrong approach. Labour would tax fairly, spend wisely, and get our economy firing on all cylinders, to ensure Britain’s pensioners can have the retirement they deserve.”

MPs have reported receiving angry letters referring to the National Insurance hike as the “poll tax 2.0”.

An impact assessment produced by HM Revenue and Customs for the Treasury warned that one effect of the 1.25 percentage point tax increase “may be an impact on family formation, stability or breakdown as individuals, who are currently just about managing financially, will see their disposable income reduce.”

The assessment, disclosed by The Telegraph in September, also stated that the new health and social care levy “is anticipated to have a significant macroeconomic impact” with consequences “for earnings, inflation and company profits”.