More than 1,200 business leaders, including more than 40 from the East of England, today backed the campaign for Britain to remain in the European Union, in a letter published in The Times.

Signatories include chairmen and chief executives from 51 FTSE 100 companies, and leaders from a number of other major businesses including Virgin Group founder Sir Richard Branson, although figures from more than 900 small and medium-sized firms have also put their names to the letter.

In the letter, they say: ““We own and run more than 1,200 businesses, from micro companies to the FTSE 100, employing more than 1.75m people.

“We know our firms are stronger in Europe. Our reasons are straightforward: businesses and their employees benefit massively from being able to trade inside the world’s largest single market without barriers. As business people, we are always looking to the future – and a future inside the European Union is where we see more opportunities for investment, growth and new jobs.

“We know that Britain leaving the EU would mean having to re-establish terms of trade from scratch with our home market of 500 million consumers. That wouldn’t just hurt exporters but the hundreds of thousands of small and medium firms who do business with them.

“Even those that want Britain to leave say that, in the short term, Brexit would lead to economic uncertainty and would put jobs at risk. Smaller businesses and the people they employ are particularly vulnerable to any economic shock which could follow a vote to leave the EU.

“Britain leaving the EU would mean uncertainty for our firms, less trade with Europe and fewer jobs. Britain remaining in the EU would mean the opposite – more certainty, more trade and more jobs. EU membership is good for business and good for British jobs. That’s why, on June 23rd, we back Britain remaining in the EU.”

Signatories of the letter from Suffolk and north Essex include Andrew Blenkiron, estate director, Euston Estate; Charlie Fillingham, managing director, Strutt & Parker (Farms), Chatham Green, near Chelsmford; Frankie Fox, co-founder of The Foraging Fox, Hatfield Broad Oak; Will Gemmill, partner at Gemmill Brothers, Stansted; Richard Herbert, chairman of Herbert Group, Haverhill; Chris Perry, managing director, Entec Industries, Stowmarket; Marc Sansom, director of SALUS Global Knowledge Exchange, Chelmsford; and Becky Sebright-King, director at Lady Bakewell-Park, Wherstead.

The Britain Stronger in Europe campaign said the scale of support for the letter “puts to bed the claim of Leave campaigners that ‘business is split’ on the Europe issue.”

However, the pro-Leave Business for Britain group lists more than 90 East of England supporters for “Brexit” on its website.

In a separate development, employees at Tate and Lyle Sugars have been told that leaving the EU would benefit the business and protect their jobs, according to a report.

A letter from one of the company’s top bosses said that positions at the firm, one of Britain’s oldest, will be safer if operations can move beyond the reach of EU tariffs and restrictions.

Employees will not be told how to vote in the message from senior vice president Gerald Mason, who said the company had been prevented from turning a profit as a result of being in the Union, the BBC reported.

He wrote: “Last year EU restrictions and tariffs pushed our raw material costs up by nearly 40m euros (£31m) alone, turning what should have been a good profit that we would all share into a 25m euro (£19m) loss.

“We pay as much as 3.5m euro (£2.7m) of import tariffs to the European Union on some of the boats of cane sugar that unload at our refinery, only for the European Union to then send that money to subsidise our beet sugar producing competitors in Europe.”