Just one third of British voters would give their unconditional support to a Brexit agreement, according to a new poll.

The ICM survey, reported in the Guardian, lends weight to growing public pressure for the Government to share its Brexit plan before the formal process of leaving Europe begins.

Prime Minister Theresa May has remained adamant her Government will push ahead with the Brexit process despite the High Court ruling last month that she would not be able to trigger Article 50 without a parliamentary vote.

However, The Independent reported on Saturday that Ms May could try and overturn the Brexit court ruling by claiming the triggering of Article 50 – officially launching withdrawal talks – has no direct impact on British citizens’ rights.

The poll, commissioned by online campaign group Avaaz, found 33 per cent of voters support Brexit unconditionally, while 23 per cent oppose it unconditionally.

32 per cent of voters said it would depend on the terms of the deal, and 12 per cent remain undecided.

Last week, a group of MPs from the Liberal Democrats, Labour and SDLP said they would vote against the triggering of Article 50.

Tim Farron, the leader of the Liberal Democrats, said his party would oppose any Brexit deal without a second referendum on its terms.

“Article 50 would proceed, but only if there is a referendum on the terms of the deal. And if the British people are not respected then, yes, that is a red line and we would vote against the Government,” he said.

The Government has already submitted its initial grounds for appeal at the Supreme Court following last month’s ruling, which do not indicate any major change from the case argued at the High Court.