Britain looks set to leave the European Union by summer 2019 after triggering the formal process to pull out before the end of March next year, Theresa May has said.

The prime minister said Article 50 of the Lisbon Treaty will be triggered in the first three months of 2017, marking the start of the two-year process to enact Brexit.

Britain’s shock vote to leave the European Union in June propelled Mrs May to power and the former interior minister has since been under pressure to offer more details on her plan for Britain’s departure, beyond her often-repeated catchphrase that “Brexit means Brexit”.

In a move to ease fears among her ruling Conservatives that she may delay the divorce, Mrs May will tell the party’s annual conference in Birmingham that she is determined to move on with the process and win the “right deal”.

Using Article 50 of the EU’s Lisbon Treaty will give Britain a two-year period to clinch one of the most complex deals in Europe since the second War Two.

“We will trigger before the end of March next year,” Mrs May told the BBC’s Andrew Marr show.

“Now that they know what our timing is going to be ... (I hope) that we’ll be able to have some preparatory work so that once the trigger comes we have a smoother process of negotiation.”

Britain’s decision to leave the EU on June 23th sparked turmoil in financial markets as investors tried to gauge its impact on both the world’s fifth largest economy and the union.

The country’s allies fear that its exit from the EU could mark a turning point in post-Cold War international affairs that will weaken the West in relation to China and Russia, undermine efforts toward European integration and hurt global free trade.

Sterling plunged to a 31-year low after the vote and is now trading around 40 US cents - or 25 per cent - lower than the six-year highs it reached in mid-2014.

‘Great Repeal Act’

For some businesses, Mrs May’s reluctance to offer what she describes as a “running commentary” on her strategy, has deepened fears that they could end up paying higher costs if operating from Britain.

Mrs May said there was “a difference between not giving any commentary and giving a running commentary”.

“What I am doing today is setting out some further detail on the timing and the way we are going to approach this whole question,” she said.

Mrs May was expected to say she would trigger the divorce procedure early next year - a move the leader hopes will show voters that she is determined to deliver Brexit despite having campaigned, albeit quietly, for Britain to remain in the union.

For many of her MPs, the announcement hit the mark.

“The timing is just right,” Conservative MP Andrew Bridgen said, saying that voters had understood that the new prime minister had needed some time to prepare her position.

Others said they feared that triggering Article 50 so early could put pressure on Britain as elections in France and Germany in 2017 could change London’s partners in the middle of talks.

Saying she did not want to give away her stance, Mrs May offered little insight into the question of where she would set the gauge in the struggle to balance controlling migration with winning tariff-free access to the EU’s single market.

She said her government must respond to the demands of voters, many of whom fear that hospitals and schools are being stretched by high levels of migration from the European Union, but also had to listen to business.

“I want the right deal for trade in goods and services and what we are doing at the moment ... is listening to businesses here in the UK, listening to different sectors, finding out what it is that is most important to them,” she said.

And she appealed to the EU, which has said “there will be no negotiations without notification”, to open talks to smooth the way for Britain’s exit.

“It’s not just important for the UK, it’s important for Europe as a whole that we are able to do this in the best possible way so we have the least disruption for businesses ... and when we leave the EU we have a smooth transition away from the EU,” Mrs May said.

Independent

But while trying to keep EU partners on board, her move to repeal next year the 1972 European Communities Act, which took Britain into what is now the EU, and make Britain “a sovereign and independent country” was aimed directly at her party.

Some members of her Conservative Party said that what the prime minister has billed as the ‘Great Repeal Act’ was little more than a technicality, but others said it was the first step for Britain to reclaim power and dispense with some EU regulation.

“I’m rather looking forward to being a sovereign parliament again ... to dealing with EU legislation and removing unnecessary laws and streamlining it,” said Mr Bridgen.