Margaret Thatcher’s former defence secretary has suspended his Conservative party membership over the “poisonous” EU referendum campaign and placed blame on David Cameron’s “tirade of fear”.

Sir John Nott, who was Baroness Thatcher’s defence chief during the Falklands war, attacked the current Tory leader for “alienating Conservatives” and said he would not renew his membership “until we have a change of leadership”. Sir John served in government between 1979 and 1983.

In a letter to the MP of his former constituency the veteran Tory politician lashed out at the Prime Minister and George Osborne, the Chancellor, for their “fairly frenetic campaign” in favour of the EU.

According to the Daily Telegraph, Sir John added: “I thought that when he [Mr Cameron] called the referendum, probably we were going to have a sensible, if not an intellectual, debate about the pros and cons of the EU.

“And I do believe that if they had set off to set out what they saw of the advantages and the disadvantages on the other side, and it had been a balanced debate, then they would quite easily have come out with a Remain conclusion.”

He added: “They launched very early into this attack, this description of all the horrors that would happen if we exit. I just listened to this and thought, ‘this is complete nonsense’.”

British Conservative Prime Minister, Margaret Thatcher, with Geoffrey Howe, Keith Joseph, John Nott, Norman Tebbit on the Conservative front bench in the House of Commons on 4 November 1981 (Getty ) (Getty)

The high-profile resignation comes as the chairman of JCB Lord Bramford wrote to his 6,500 UK employees to explain why he favours a vote to leave the EU. The billionaire businessman, who has donated millions of pounds to the Tory party in the past 15 years, told his staff leaving the bloc was of “diminishing economic importance”.

He also said that more than 53 per cent of all UK exports go to non-EU nations.

His letter states: “I voted to stay in the Common Market in 1975. I did not vote for a political union, I did not expect us to hand over sovereignty to the EU.

What has the EU ever done for us? Show all 7 1 /7 What has the EU ever done for us? What has the EU ever done for us? 1. It gives you freedom to live, work and retire anywhere in Europe As a member of the EU, UK citizens benefit from freedom of movement across the continent. Considered one of the so-called four pillars of the European Union, this freedom allows all EU citizens to live, work and travel in other member states. What has the EU ever done for us? 2. It sustains millions of jobs A report by the Centre for Economics and Business Research, released in October 2015, suggested 3.1 million British jobs were linked to the UK’s exports to the EU. What has the EU ever done for us? 3. Your holiday is much easier - and safer Freedom to travel is one of the most exercised benefits of EU membership, with Britons having made 31 million visits to the EU in 2014 alone. But a lot of the benefits of being an EU citizen are either taken for granted or go unnoticed. What has the EU ever done for us? 4. It means you're less likely to get ripped off Consumer protection is a key benefit of the EU’s single market, and ensures members of the British public receive equal consumer rights when shopping anywhere in Europe. What has the EU ever done for us? 5. It offers greater protection from terrorists, paedophiles, people traffickers and cyber-crime Another example of a lesser-known advantage of EU membership is the benefit of cross-country coordination and cooperation in the fight against crime. What has the EU ever done for us? 6. Our businesses depend on it According to 71% of all members of the Confederation of British Influence (CBI), and 67 per cent of small and medium-sized enterprises (SMEs), the EU has had an overall positive impact on their business. What has the EU ever done for us? 7. We have greater influence Robin Niblett, Director of think-tank Chatham House, stated in a report published last year: “For a mid-sized country like the UK, which will never again be economically dominant either globally or regionally, and whose diplomatic and military resources are declining in relative terms, being a major player in a strong regional institution can offer a critical lever for international influence.

“I certainly did not expect unaccountable leaders in Brussels to govern over us.

“So do I wish to remain in an EU of diminishing economic importance as it moves towards ever closer union? Or do I want us to pull out of the EU, reclaim our sovereignty and regain control of how we trade with Europe and the world?”