Drafting ‘error’ led to Gen Sir Michael Rose being listed as signatory of letter by former military heads who oppose UK exit

Downing Street has apologised to General Sir Michael Rose after wrongly including him in a list of former military chiefs who oppose the UK leaving the EU.

A No 10 spokesman said the former special forces chief’s name appeared on the list because of a “mistake” in the drafting of the letter, which was handed to the Daily Telegraph for publication in its Wednesday newspaper.

The letter was purportedly signed by 13 former military chiefs and said Europe faced a series of “grave security challenges” and that the UK was in a “stronger” position to deal with them from inside the EU. Signatories included field marshals Lord Bramall and Lord Guthrie, an air chief marshal, Lord Stirrup, an admiral of the fleet, Lord Boyce, and Rose, a former special forces chief.

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But it is understood Downing Street was told by Rose on Wednesday morning that he had not signed the letter, even though he had seen a draft that was circulated to him. A No 10 spokesman would not elaborate on how the mistake came about.

The error comes after leave campaigners questioned the worth of a previous letter organised by No 10 signed by 36 FTSE 100 chiefs warning against a Brexit.

Leave campaigners point out that two-thirds of FTSE 100 companies, including Tesco and Sainsbury’s, did not back the letter.

Letters of endorsement from business chiefs for David Cameron have previously fallen apart during the general election.

A letter of support for the Conservatives from 5,000 small business owners unravelled during the 2015 campaign after it emerged it contained dozens of duplicate names and one person who said they had never signed it.

Those campaigning to keep Britain in the EU believe a steady stream of warnings from military chiefs, businesses and other professions will begin to make the public think twice about the risks of Brexit. Leave campaigners have dubbed the strategy “Project Fear”.

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In the letter to the Telegraph, the former military chiefs told of their concern about the rise of Islamic State, saying: “We have served around the world and in almost every conflict in which Britain has been engaged since the second world war.

“We are proud to have served our country and to have played our part in keeping Britain safe. In the forthcoming referendum, therefore, we are particularly concerned with one central question: will Britain be safer inside the EU or outside it? When we look at the world today, there seems to us only one answer.

“Europe today is facing a series of grave security challenges, from instability in the Middle East and the rise of Daesh [another name for Isis], to resurgent Russian nationalism and aggression.

“Britain will have to confront these challenges whether it is inside or outside the EU. But within the EU, we are stronger. Inside it, we can continue to collaborate closely with our European allies, just as we did when we helped to force the Iranians to the negotiating table through EU-wide sanctions, or made sure that Putin would pay a price for his aggression in Ukraine.”