A deal preserving the Common Travel Area between the UK and Ireland after Brexit has been signed.
The memorandum of understanding between the two governments allows citizens of both countries to move freely between Great Britain and the Republic of Ireland.
It also allows for cross-border access to education and healthcare.
The non-legally binding understanding was signed by senior UK and Irish ministers at a Cabinet Office meeting of the British-Irish Intergovernmental Conference in London on Wednesday.
The conference was part of a renewed bid to restore devolved powersharing at Stormont, initiated after the murder of journalist Lyra McKee in Londonderry last month.
Common Travel Area not legally binding
The CTA predates the UK and Ireland's membership of the EU.
There was no legally binding international agreement which established its terms and it was largely based on trust.
The memo is an attempt to reinforce that understanding.
It was signed by the UK's de facto deputy prime minister David Lidington and Irish deputy premier Simon Coveney, with Northern Ireland Secretary Karen Bradley and Irish justice minister Charlie Flanagan in attendance.
Mr Lidington said: "This memorandum of understanding highlights the value both of our governments place on the CTA - a long-standing, cherished set of arrangements that have real significance in people's day-to-day lives.
Mr Lidington continued: "Today's announcement reflects close work with Ireland over the last two years to ensure that the CTA and associated rights are maintained, no matter the terms of the UK's withdrawal from the EU."
Mr Coveney said: "Today marks an important moment for the long-standing Common Travel Area arrangement between our two countries.
"The CTA has provided rights and privileges to Irish and British citizens for nearly a century.
"However, it has not before been formalised in this way."
The Tanaiste added: "The CTA is a practical demonstration of the enduring strength of the British-Irish relationship and of our people to people ties.
"I want to assure British citizens living in Ireland that they are welcome and truly valued here, as is their contribution to Ireland and Irish life.
"British citizens will continue to be able to travel freely, live, study and work in Ireland into the future.
"I welcome the similar commitment and welcome of the UK Government for Irish citizens in Britain."
Fresh powersharing talks
The intergovernmental conference is provided for by the 1998 Good Friday Agreement and facilitates bilateral co-operation between Britain and Ireland.
It was resurrected after seldom being used because of the absence of a breakthrough at Stormont.
The fresh powersharing talks process began in Belfast on Tuesday.
Leaders of the five main parties acknowledged mounting public impatience and anger at a stalemate that has left the region without a functioning devolved government for more than two years.
They held a short round-table meeting at Stormont House on Tuesday afternoon for the first exchanges of a new process initiated by the UK and Irish governments.
The process will involve agenda-setting and stock-taking meetings between the five leaders and two governments at least once a week, with five working groups to focus on the detail of key disputes at the heart of the deadlock.