George Osborne faces another tough day over the tax credits debacle. The Conservatives have been attacked over their record on poverty by two former prime ministers today, while a Tory MP urges a “rethink” on their plan to slash tax credits.

Former Tory PM John Major has said that the level of inequality in the country is “shocking”, and Gordon Brown has launched an attack on the Tory tax credit plans. Brown, who introduced tax credits as Chancellor, writes in today’s Mirror that the Government’s reforms will leave Britain with “one of the biggest poverty problems in the western world”.

Meanwhile, Heidi Allen, a Conservative backbencher, says that the tax credits defeat in the Lords has presented the Government with “an opportunity to rethink its approach to tax credits and find a solution that does not impact so severely those on low pay.”

The mounting pressure on Osborne comes as a new report from the Work and Pensions Committee, which Allen sits on, warns that money for lessen the impact of tax credit changes should not come out of the budget for Universal Credit. They say this could put people off from finding work.

Shadow Treasury minister Rebecca Long-Bailey said the report comes as “a huge blow to the Chancellor.” She added that Osborne’s mishandling of the situation has led to discontent on the Government backbenches. “Now his inability to take a lead on this issue is seeing even Tory MPs follow Labour proposals,” she said.

In a lecture he will deliver tonight, Major will describe the level of poverty in Britain as in “a shocking situation in 2015.” He will add: “As the world becomes richer, inequality becomes less tolerable, and the case for reducing it more urgent.”