Theresa May stamps her authority on Brexit plans after Boris Johnson strays from the script

The Foreign Secretary had predicted Britain could leave the bloc by the end of 2018

Downing Street has asserted its authority over Boris Johnson after he strayed from the official line and speculated on when the Government would eventually trigger Article 50.

A Number 10 source told The Independent: “The Government’s position has not changed – we will not trigger Article 50 before the end of 2016 and we are using this time to prepare for negotiations.”

It comes after Mr Johnson suggested Britain could leave the bloc by the end of 2018 and predicted it would take less time than the two years maximum allowed under the Lisbon Treaty. But the Government indicated triggering Article 50, the untested protocol for leaving the EU, would ultimately be Ms May’s decision.

Speaking in New York, where he was attending the United Nations summit, Mr Johnson appeared to go against the Government’s often-repeated line that they will “not give a running commentary” on the Brexit negotiations.

He added: “By the early part of next year, you will see an Article 50 letter which we will invoke and, in that letter, I am sure we will be setting out some parameters for how we propose to take this forward. You invoke Article 50 in the early part of next year (and) you have two years to pull it off. I don’t actually think you need to spend the full two years, but let’s see how we go.

“We are going to benefit from fantastic opportunities for free trade with our friends in the EU. Not only do we buy more German cars than anybody else, we drink more Italian wine than everyone else – they're not going to put that at risk.”

However, it is widely believed that the process of leaving will take at least the full two years. Further time can be granted, but only if the other 27 EU states unanimously agree to grant an extension.

The Foreign Secretary also hailed “fantastic opportunities for free trade”, pouring scorn on warnings that the EU will play tough in the Brexit talks.

His comments came after Martin Schulz, President of the European Parliament, arrived in Downing Street and urged Ms May to get the process of leaving the EU moving. He said the European Parliament wanted Britain to have completed the exit process by early 2019. He argued it would be wrong for British voters to take part in EU Parliament elections – in June 2019 – while the negotiations were ongoing.