BRITAIN’S middle and high earners could face a tax raid under a future Conservative government, Theresa May has indicated, as she signalled an end to the Tories’ flagship tax lock pledge on workers’ income.

The Prime Minister ruled out a rise in VAT, but not on income tax or National Insurance (NI), as she said her priority was to ensure the tax system was “balanced”, stressing that her intention was to “reduce taxes on working families”.

Mrs May told BBC One’s Andrew Marr Show: “We have absolutely no plans to increase the level of tax, but I’m also very clear that we don’t want to make specific proposals on taxes unless I’m absolutely sure that I can deliver on those.”

In his March Budget, Philip Hammond had to perform an embarrassing U-turn on raising NI contributions for Britain’s five million-strong army of the self-employed – the so-called “white van man tax” – given the 2015 manifesto had pledged not to raise taxes.

The Prime Minister now looks set to give any future Conservative government the “flexibility” the Chancellor craves.

But Andrew Gwynne, Labour’s election co-ordinator, said: “The Prime Minister refused to rule out hitting working people with more taxes. While she said she had ‘no plans’ to raise VAT, people should remember that’s what the Tories said before 2010, then did just that.”

Labour leader Jeremy Corbyn also suggested taxes would rise if he took power, but only for those “very much at the top end”. Low and middle income earners would be protected, he insisted.

Earlier this year, Holyrood made history by voting to set separate Scottish income tax rates and bands for the first time.

The SNP and Greens agreed a deal which left the basic rate, paid by most taxpayers, unchanged, but reduced the threshold for paying the 40p rate to £43,000 in Scotland, instead of the £45,000 elsewhere in the UK.

The change means people earning more than £43,000 in Scotland will pay up to £400 more than those on the same salary in other parts of the UK.

After being challenged by shadow chancellor John McDonnell to rule out a rise in VAT if the Tories won power, Mrs May did so but dodged the issue on whether or not the party’s 2015 manifesto tax lock – which also rules out increases to income tax and NI – would be kept, raising speculation that it will not be.

Mrs May also indicated that another flagship Tory policy, the triple lock on pensions, would go.

She told the Marr show: “Under a Conservative government the state pension will still go up every year of the next parliament. Exactly how we calculate that increase will be for the manifesto and, as I have just said, you will have to wait for the manifesto to see what’s in it.”

Labour has pledged to maintain the triple lock, which sees state pensions rise each year by the highest of inflation, earnings or 2.5 per cent.

Mr McDonnell claimed breaking it would plunge some of Britain’s poorest pensioners into poverty.

“I do not want to go backwards, I do not want pensioners going back into poverty again,” he declared.

In a separate development, the Prime Minister came under fire over nurses’ pay and the use of food banks, with Marr quoting figures from the Royal College of Nursing which suggested nurses have had a real-terms 14 per cent pay cut since 2010, with some reportedly turning to food banks because they could not afford to feed themselves.

Mrs May argued that there were “many complex reasons” why people used food banks, stressing how she wanted a strong economy to pay for public services and “where we’re creating secure jobs, and well-paid jobs, and higher paid jobs for people”.

But Janet Davies, the RCN Chief Executive, criticised Mrs May and said the one per cent cap on public sector basic pay increases was “fuelling a recruitment and retention crisis” that was risking patient safety.

“Nurses should not have to fund the NHS deficit from their own pay packets. Too many are struggling to make ends meet, turning to food banks and hardship grants in desperation,” she declared.

Labour’s Angela Eagle took to Twitter to criticise Mrs May’s “appalling refusal to recognise the human cost of Tory cuts”.

The SNP’s Stuart Donaldson said: “Theresa May has confirmed the real cost of voting for the Tories; continued austerity, continued reliance on food banks, cuts to education spending that will hit Scotland’s budget, and uncertainty for pensioners who will be hit in the pocket.

Today in Scotland, Lord Darling of Roulanish, the former Chancellor, will be campaigning to help Ian Murray hold onto his Edinburgh South seat, the only one Labour won in the 2015 SNP landslide.

The Labour peer, hitting the campaign trail in the capital to mark 20 years since Labour’s 1997 landslide election victory, Mr Darling said: “Labour’s proud record shows what can be achieved when a government focuses on the day job. The priority of a Labour government is always to grow the economy, create jobs, lift people out of poverty and give everybody a fair chance in life, not seeking to divide the country.”

He insisted First Minister Nicola Sturgeon and her colleagues must respect the mandate the Scottish people gave in 2014 and rule out another unwanted and divisive independence referendum.

“Scotland is divided enough. The majority of people in Scotland believe that together we’re stronger by remaining in the UK,” insisted Lord Darling.

Holyrood has made history by voting to set separate Scottish income tax rates and bands for the first time.

The SNP and Greens have agreed a deal which will see the basic rate, paid by most taxpayers, left alone.

But the threshold for paying the 40p rate will start at £43,000 in Scotland instead of the £45,000 elsewhere.

The income tax changes will mean people earning more than £43,000 in Scotland will pay up to £400 more than those on the same salary elsewhere in the UK.

The minority SNP administration had initially planned to raise the threshold for the 40p rate only in line with inflation, instead of increasing it to £45,000 as the UK government has done.

But in striking a deal with the Scottish Greens to get its budget plans through parliament, the proposed rise was scrapped and the threshold was instead frozen at £43,000.

The Scottish Conservatives warned the move will damage Scotland by making it the “highest taxed part of the UK”, while Labour and the Liberal Democrats - who both favoured limited tax increases to protect services - accused the government of being too timid with its new income tax powers.