The UK's House of Commons has voted by the more than the required two-thirds majority to hold a General Election on Thursday, June 8, this year rather than in May 2020. By calling a General Election the Prime Minister is seeking to turn a significant lead in the polls into a far larger Government majority in Parliament than she currently has.

If she is successful, she will have a strong mandate to stamp her authority on the conduct of the Brexit negotiations. Parliament is also more likely to pass the raft of legislation necessary to implement Brexit, and with fewer amendments.

Sterling rose to its highest level against the dollar for five months in response to the Prime Minister’s announcement, reflecting a belief that a larger Government majority would limit the influence of pro-Brexit hardliners within the Conservative party, and that a negotiated settlement would be more likely than the cliff edge of no deal at all.

As importantly, however, the Prime Minister’s decision was motivated by a growing realisation that the pressure of a General Election in 2020 could have jeopardised a successful outcome to the negotiations. The UK has until March 29 2019 to negotiate and implement its withdrawal from the EU (unless the two-year period is extended with the agreement of all EU Member States, which is unlikely).

The prime minister told the BBC Today programme this week: "If you look at the timetable, had the election been in 2020 we would have been coming up to the most crucial part of the negotiations - in what would have started to be the run-up to a general election."

The Government has also set itself the task of negotiating a new relationship with the EU in the same timeframe, to be implemented in a phased approach thereafter. It is widely agreed (outside Government) that two years is a wholly unrealistic timeframe for a successful outcome to negotiations of this importance and complexity, and that transitional arrangements will be needed to bridge the gap of five years or more between the UK’s withdrawal from the EU and the negotiation and implementation of the new relationship agreement.

By delaying the next General Election until May 2022 (under the 2011 Fixed Term Parliaments Act, General Elections take place every five years unless the House of Commons votes by a two-thirds majority to hold an earlier election) the Prime Minister is in effect taking the pressure off herself to complete the negotiation of the UK’s withdrawal and new relationship with the EU in two years, ahead of a General Election in 2020.

A gap of three years between withdrawal in 2019 and a General Election in 2022 gives her greater flexibility to accept politically difficult compromises as part of transitional arrangements, such as allowing for free movement of people or the jurisdiction of the Court of Justice of the EU, before going to the polls. Such compromises might not have been acceptable were a General Election to have been held in 2020.

The EU knows that it is easier to carry out a successful negotiation with a Government that has a clear national mandate to conduct the negotiations, and to that extent it has reacted positively to the announcement. It knows too that a large Government majority will make it harder for UK negotiators to claim that Parliamentary approval will not be forthcoming without further concessions from the EU. Nor will a UK General Election in June upset the Brussels timetable for the Brexit negotiations.

The European Council (formed of Heads of State or Government of the EU Member States) will publish its Guidelines for the negotiations on 29 April. These will then be incorporated into the detailed Recommendations which the Commission (the EU’s executive) will draft and adopt during May, and send to the Council (formed of Governments of the EU Member States) in early June. The Council will adopt a formal mandate authorising the opening of the negotiations shortly thereafter.

Continuity and legal certainty in commercial relations between the UK and EU will be vital in the period between the UK’s formal withdrawal from the EU and the negotiation and coming into force of the agreement setting out its new relationship with the EU. This can best be provided by transitional arrangements being put in place, most likely as part of the UK’s withdrawal agreement.