Bannatyne joins 100 business leaders backing Conservative-led government in letter to the Daily Telegraph

The signatories support Conservative proposals to lower corporation tax to 20 per cent and political commentators are describing it as a significant intervention with 36 days to go to the general election.

Other business leaders who signed the letter include BP chief executive Bob Dudley, Prudential boss Tidjane Thiam, Carillion chairman Philip Green and ASOS chief executive Nick Robertson.

Labour has dismissed the letter, saying it would prioritise lower business rates for small firms.

The letter was released as it emerged Mr Miliband is to promise legislation in a Labour government's first Queen's Speech guaranteeing employees the right to a regular contract after 12 weeks of working regular hours in practice with an employer.

The commitment - to be included in the party's election manifesto - significantly strengthens its previous policy entitling workers to a regular contract after 12 months.

In their letter the executives - who come from some the country's best known companies - praised the Government's economic policies, which they said had supported investment and jobs.

In particular they highlighted Chancellor George Osborne's policy of progressively lowering corporation tax to 20 per cent - which they said had been a "key part" of the Government's economic plan.

Just hours earlier shadow chancellor Ed Balls announced that a Labour government would reverse the final reduction - due to take effect later this month - in order to hand a cut in business rates to small firms.

"It has been a key part of their (the Government's) economic plan," the executives said in their letter.

"The result is that Britain grew faster than any other major economy last year and businesses like ours have created over 1.85 million new jobs.

"We believe a change in course will threaten jobs and deter investment. This would send a negative message about Britain and put the recovery at risk."

As well as Mr Bannatyne, other signatories to the letter include BP chief executive Bob Dudley, Prudential chief executive Tidjane Thiam and Sir Charles Dunstone, the chairman of Dixons Carphone and Talk Talk plc.

Mr Miliband chose to seize on the issue of zero hours contracts after David Cameron admitted during his televised grilling last week by Jeremy Paxman that he could not live on one.

Mr Miliband, who will set out his proposals at a campaign event today in Yorkshire, will say that the proliferation of zero hours contracts has come to symbolise the failure of the Conservative-led coalition's economic policies.

He is expected to say: "What's really worrying is that David Cameron isn't worried. Why should he? It's his plan for the economy. Do you remember what he told Jeremy Paxman last week when he was asked why are more and more people trapped on zero hours contracts?

"He didn't say it was because low paid, low skilled work is booming on his watch. No, he said it was because people really want to be on them.

"Then he admitted he couldn't live on one himself. Well, I say, if it's not good enough for him, it's not good enough for you. And it's not good enough for Britain either.

"These zero hours contracts have become a symbol of the Tories' failing economy with stagnant wages and falling productivity leaving a recovery which isn't reaching your front door and a deficit still at Downing Street's door.

"We will give working people more control of their working lives, we're going to put an end to exploitative zero hours contracts."

Labour officials said that while there would be exemptions for employees such as so-called bank nurses who specifically request a zero hours contract so they can work at another hospital as well as their usual job - more than 90 per cent of the 1.8 million existing zero hours contracts would be banned.

The proposals were strongly criticised by CBI director-general John Cridland who warned that it could prove counter productive creating more instability for workers.

"Of course action should be taken to tackle abuses, but demonising flexible contracts is playing with the jobs that many firms and many workers value and need," he said.

"These proposals run the risk of a return to day-to-day hiring in parts of the economy, with lower stability for workers and fewer opportunities for people to break out of low pay."

The Conservatives said that just one in 50 jobs were zero hours contracts and that the Government had already acted to tackle abuses.

"Labour presided over zero hours contracts with no safeguards for three terms and 13 years while they were in power. Tony Blair even promised to ban them entirely as far as back as 1995 and then did nothing," a spokesman.

"The fact is that three quarters of the new jobs since this Government came to office are full time - these are families across the country getting into work with the security of a regular pay packet.

The plans were however warmly welcomed by the trade unions. TUC general secretary Frances O'Grady said: "Zero-hours workers are often too afraid to speak up for their rights for fear of losing work.

"We need a fairer system that guarantees zero-hours workers decent rights at work and stops them from being treated like second-class employees."

For Labour, shadow business secretary Chuka Umunna dismissed the letter from the executives as "nothing new".

He said: "No one will be surprised that some business people are calling for low taxes for big businesses. That's nothing new and under Labour Britain will have the most competitive corporation tax rate in the G7.

"But whilst the recovery may have reached some firms it hasn't reached many others which is why we will prioritise tax cuts for the smallest firms with an immediate cut in business rates for 1.5 million small business premises.

"We don't believe, as David Cameron does, in more tax cuts for the richest in society - the priority is tax cuts for small firms, working people and saving our NHS."

Chancellor George Osborne said: "An intervention on this scale and with this clarity from Britain's business leaders is unprecedented in any recent general election.

"Over 100 business leaders, heading up some of our largest companies and most famous brands, and employing over half a million people, have spoken out.

"Their message is positive: under David Cameron's leadership, we have an economic plan that is working and creating jobs. Today that plan sees corporation tax cut again to 20pc, and a new diverted profits tax so those low taxes are paid.

"And the warning from Britain's business leaders couldn't be clearer: a change of course will threaten jobs, deter investment, send a negative signal about our country and put the recovery at risk.

"Britain now knows. No more ifs or buts.

"Vote for Ed Miliband and Ed Balls on 7th May, and jobs and investment and economic recovery will be at risk. Now, more than ever, Britain should stick with the plan that's working."

Mr Cameron said in a message on Twitter: "Today's business letter in the Telegraph shows job creators support our long-term economic plan. Labour's taxes will cost jobs."

In an interview recorded before the publication of the Telegraph letter, Mr Miliband suggested that the economic recovery was being felt by the richest more than by ordinary families.

The Labour leader told the BBC: "David Cameron says it has all been a great success. I will let the British people be the judge of that. But what I see is living standards and wages down over five years and people really struggling."

Challenged over figures which Mr Osborne has said show living standards are higher than in 2010, Mr Miliband said: "There are different measures around on this, but I'm pretty clear that wages are down, living standards are down and that's what people feel. They feel this is a recovery that might have reached the City of London but it hasn't reached them, and that is what we have got to change."

Asked if a Labour government would put up taxes, Mr Miliband said: "That's not the way we raise living standards, no. We have ruled out a rise in national insurance and VAT and income tax rates."

Wealthier people would be asked to pay a 50p income tax rate on earnings over £150,000 and a mansion tax on properties worth over £2m under Labour, because "I have a simple principle that those with the broadest shoulders should bear the greatest burden".

Conservative peer and ex-M&S boss Stuart Rose accepted that the number of zero-hours contracts should be reduced but denied they were being "abused" by employers and insisted Labour's tough restrictions were not the solution.

Lord Rose, who was among the signatories to the letter, told BBC Radio 4's Today: "It is a good ambition of course over time to reduce the number of zero-hours contracts.

"I think the total number of zero-hours contracts in the workforce is something like two per cent. Clearly everybody would want to get that down but the most important thing first is to create more secure jobs.

"If you create more secure jobs you will allow over time for us to reduce the number of zero-hours contracts.

"I seem to remember ten years ago Tony Blair suggested that they would reduce zero-hours contracts. Ten years later we are all trying. It's a laudable ambition but you can't do it by legislation."

Asked whether small businesses would prefer a rates cut, he said: "Businesses always want something, always need something. The good news at the moment is that we have got this flourishing environment and we have got record numbers of start-ups.

"Businesses are actually reasonably happy at the moment because they know that the environment into which they are trying to invest, trying to expand, trying to drive their business, is allowing them to do that.

"Clearly they would always want something else but it's a question of choices we have to make."

He added: "Look at the large number of people who have signed it. Look at the diverse backgrounds they come from, whether they're small businesses, medium-sized businesses or large businesses. That must say something."

The letter is particularly awkward for Mr Miliband because it carries the signatures of at least five bosses who have in the past offered some backing to Labour, as well as the chairman of Bloomberg, which hosted the launch of the party's business manifesto earlier this week.

Former Labour supporters included Mr Bannatyne, who backed Gordon Brown in 2010; hotelier Surinder Arora, who the Telegraph said had been described as "a big fan" of Tony Blair; Dixons Carphone and TalkTalk chairman Sir Charles Dunstone, who endorsed Mr Blair in 2005; theatrical producer Sir Cameron Mackintosh, who donated money to Labour in the 1990s; and businessman Moni Varma, who gave the party £10,000 in 2001.

However, Sir Cameron has since made large donations to the Tories, and several other signatories have links to the party, including Conservative peers Lord Rose, Lord Bamford and Baroness (Karren) Brady.

Labour former deputy prime minister John Prescott dismissed the signatories to the letter as "Tax Dodgers, Tory Voters and non Doms" in a reworked version of the newspaper's front page posted on Twitter.