Almost half of British people do not believe the Government will conclude the process of leaving the European Union by March 2019, according to a new poll for The Independent.

It comes as Theresa May prepares to invoke Article 50, the untested mechanism for a member state leaving the EU, within the next two weeks ahead of her self-imposed deadline at the end of March.

The activation of Article 50 starts the two-year countdown on Britain’s exit from the EU. For an extension to be granted for the negotiation period – if Downing Street fails to reach an agreement by March 2019 – there will need to be a unanimous decision by the 27 other member states.

But according to the poll by ComRes for The Independent, 47 per cent of respondents agreed with the statement: “I do not expect Britain to conclude the process of leaving the EU within the two years, as currently planned”. Just 32 per cent disagreed while 21 per replied, “don’t know”.

While there is no clear majority, it is clear the British public has little confidence in the ability of the UK negotiators to strike an agreement by March 2019.

Earlier this week Pascal Lamy, director general of the World Trade Organisation (WTO) between 2005 and 2013, said a comprehensive free trade deal between the UK and EU could take five to six years to negotiate.

“Many of us, including me, believe that there is no way of removing the egg from the omelette in two years,” the former EU official said at an event in London hosted by the think-tank Institute for Government.

The poll also reveals that the British public are split over the Brexit process, with roughly equal proportions agreeing that Parliament should be able to veto the Government’s Brexit deal.

Just over 40 per cent of respondents disagreed with the statement “Parliament should be able to veto the Government’s proposed Brexit deal once it has been negotiated” while 38 per cent agreed and 21 per cent said “don’t know”.