It makes clear that the Government will treat the British Isles as one common travel area after Brexit and not vet those who cross from Ireland - in the EU – into the UK.

British immigration officials will rely on guards at Ireland’s border to carry out security checks on immigrants into the EU.

It says: “When considering the nature of the Common Travel Area as a border-free zone, it is important to note that immigration controls are not, and never have been, solely about the ability to prevent and control entry at the UK’s physical border.”

Officials at the Department for Exiting the EU defended the decision to allow free access to EU nationals over the Irish border.

One said: “We were never coming up with UK immigration proposals that would require you to put immigration posts between Northern Ireland and Ireland, or Ireland and GB.”