Johnson feared that Brexit vote could revive Scottish independence drive

Boris Johnson had warned that Brexit could lead to Scotland leaving the UK in a previously unseen newspaper column.

The Foreign Secretary wrote the unpublished Remainbacking article only two days before shocking David Cameron by revealing he would be campaigning for Brexit.

Setting out the dangers of Brexit, Mr Johnson states: “There is the worry about Scotland, and the possibility that an English-only Leave vote could lead to the break-up of the Union.”

In the end 62 per cent of Scots backed Remain, but the strength of votes south of the Border – including a Brexit majority in Wales – swung the result in favour of Leave.

Nicola Sturgeon warned after the result that she would consider a second independence vote to protect Scotland’s relations with the EU and will publish a referendum bill for consultation this week. 0 Boris Johnson: wrote of fears before backing Brexit

Mr Johnson is now seen as a backer of a “hard Brexit”, this week insisting the UK can get a trade deal that is “of greater value” to the economy than access to the EU single market, which he described as an “increasingly useless” concept.

But in the pro-eu article, revealed in a new book and published in The Sunday Times, he supported membership of the free trade zone.

“This is a market on our doorstep, ready for further exploitation by British firms,” Mr Johnson wrote.

“The membership fee seems rather small for all that access. Why are we so determined to turn our back on it?”

Sources close to Mr Johnson said he wrote the article for the sole purpose of trying to articulate in his mind whether there was any merit in the Remain argument and dismissed it out of hand as soon as he finished.

He also warned that Brexit would cause an “economic shock” and could lead to the break-up of the United Kingdom in the article published in All Out War, by the newspaper’s political editor Tim Shipman.

Since the vote to leave the EU the pound has fallen to historic lows, losing around 18 per cent of its value against the US dollar.

Mr Johnson said the revised deal on EU membership secured by the previous prime minister was a “bit of a dud” but was enough to ensure the UK was “not part of the federalist project.”

“I am going to muffle my disappointment and back the prime minister,” he added.