Northern Irish parties would have opt-out vote every four years
compared with Britain to ensure that there is no hard border in Ireland.
Northern Ireland would legally remain in the UK customs territory but would be aligned to EU single market rules on goods and agricultural products.
Customs checks would have to be made on goods crossing the Irish Sea, with businesses in Northern Ireland potentially claiming a rebate on goods that remained within the province, if the UK has lower tariffs than the EU under future trade deals.
Northern Ireland’s political parties would also have a consent mechanism so that they could vote every four years on whether to opt out of the arrangement and rejoin the EU customs union.
Mr Johnson also wants Britain to agree a free trade deal with Europe, rather than replicating Mrs May’s high alignment model that would have effectively yoked Britain to the EU.
The Government will today table a Commons motion formally requesting a special sitting of Parliament on Saturday – the first time since the Falklands conflict in 1982 that MPS and peers will have sat at a weekend.
The Liberal Democrats indicated they would table an amendment to Saturday’s vote calling for a second referendum to ratify any deal passed by Parliament. Such a move could also be backed by Labour, which has made a second referendum its official policy.
However, if the Government has the support of the DUP, the ERG and socalled Tory rebels, together with a handful of Leave-supporting Labour MPS, it would feel confident of defeating such an amendment and winning the vote on a deal.
Sources among the 20 former Tory MPS who had the whip withdrawn after defying the Government said the majority of them were prepared to back a deal.
Philip Hammond, the former chancellor, said: “It’s not impossible that I could vote for a deal.” But he said he would have to see the full text first.
Bim Afolami, the Tory MP, said the Prime Minister’s reference to the Hillary Step of Everest meant that the summit was just ahead and “shrouded in cloud”. He added: “But we can see it and we will get there.”