Secretary of State for Business and Trade and President of the Board of Trade Jonathan Reynolds arrives in Downing Street

Deputy Prime Minister Angela Rayner arrives in Downing Street, London, for a Cabinet meeting

At present, for industrial action to be legal, at least half of union members must vote in ballots. Forty per cent must also be in support of walkouts.

But under the overhaul, drawn up by Angela Rayner and Jonathan Reynolds, these thresholds would be ditched.

The Deputy Prime Minister and Business Secretary have pressed ahead with the proposals despite admitting in the official document outlining them that ‘reverting to legislation which is nearly 30 years old may not reflect the requirements of a modern economy.’

It apparently undermines the Government’s claim that it is ‘pro-growth’ and ‘pro-business.’

Former Tory leader Sir Iain Duncan Smith said: ‘It’s terrifying. But this should not surprise anyone.

‘The unions are Labour’s paymasters and this is just the latest example of ministers caving into them and doing their bidding.

‘This is payback for all the donations they’ve given Labour over the years.

‘If we’re not careful, we’re heading towards all the lessons learned in the 1970s being reversed and the unions just being able to hold the country to ransom and take a wrecking ball to the economy without any real mandate.’

Details of the planned overhaul were slipped out by the Government on Monday amid a wider backlash over Ms Rayner’s workers’ rights bonanza, which is set to cost firms up to £5billion a year.

They will now go out to consultation.

Angela Rayner and Transport Secretary Louise Haigh (pictured) are close allies of the unions

The consultation document states: ‘The proposed changes mean a trade union will need a simple majority of trade union members who responded to the ballot to vote in favour of the action.

‘For example, if 100 members are balloted, of whom 25 vote in favour of industrial action and 15 against, then the trade union would secure a legal mandate for action.’

Referring to the existing law, it adds: ‘Section 3 of the 2016 Act brought in a requirement to secure 40 per cent support in strike ballots for six important public services.

‘This means that if 100 members are balloted, at least 50 must vote and at least 40 vote yes… This requirement is being repealed though the Employment Rights Bill.’

The ‘important public services’ that the existing thresholds relate to are the education of children under 17, fire, health, border security, transport and nuclear decommissioning.

They were enshrined by the Tories in the Trade Union Act 2016 to help protect the public from hard-Left union bosses.

For instance, a planned nurses strike did not go ahead in June 2023 because only 43 per cent of Royal College of Nursing members voted.

But under the changes, this would have gone ahead because a majority of the 43 per cent voted in favour of industrial action.

Ms Rayner and Transport Secretary Louise Haigh, who was snapped in Whitehall this week sporting brighter red hair than usual after having it re-dyed, are close allies of the unions.

The pair were hailed by RMT rail union boss Mick Lynch during a hard-Left at Labour’s party conference last month, when he described them as ‘leading individuals’ who ‘must be ‘supported by the [union] movement.’

Both Cabinet Ministers have banked thousands of pounds of donations from trade unions in recent years, while the Labour party has accepted millions.

The proposals are part of a suite of measures that would hand greater powers to unions bosses.

They also include extending a positive ballot’s validity to 12 months. At present, union bosses must ballot members every six months to seek a fresh strike mandate.

This change will save them money and mean they can announce strikes over a year rather than just six months.

The Business Department was contacted for comment.