My thanks to commenter Jag for drawing attention to a quite a different Brexit bombshell from No 10 in the Daily Telegraph.

The Prime Minister is expected to say that EU citizens who travel to Britain after she triggers Article 50 will no longer have the automatic right to stay in the UK permanently. They will instead be subject to migration curbs after Britain leaves the European Union, which could include a new visa regime and restricted access to benefits.

If the report is accurate, it appears to run flatly counter to the assurances given by both sides over continuing the Common Travel Area and badly needs clarification. Even more than the principle of the thing which has been foreseen by lawyers, is the suddenness and speed with which the measure has been sprung, linked to triggering Art 50 by the end of March. It feels oppressive as it seems to contradict all those assurances, like those about an open border. It would surely be open to legal challenge. However I assume the CTA remains in force at least until Brexit terms on free entry are finalised.

Bizarrely, any change to the rules on free entry to Great Britain (note, not the United Kingdom ) may affect Northern Ireland people holding Irish passports. For how on entry to Great Britain can an Irish citizen from the north be distinguished from one from the south without tracing back birth place and residence? In Irish terms and probably British terms under the GFA, there is no legal distinction. So this restriction would seem to apply to Northerners who are Irish passport holders. They automatically enjoy British citizen rights but may need to acquire a British passport to assert them in Great Britain.

This development would reverse the whole trend of a creative form of unity, first dating back to ease the impact of the truamas of partition almost a century ago and then in our own time so carefully reconstructed and imaginatively accommodated within the constitutional arrangements, not only of Ireland but the whole British Isles ; and it would cast a shadow over British-Irish reconciliation. It will also do nothing, to put it mildly, to advance Theresa May’s other aim of protecting the Union, discussed below.

One way round it may be for Irish citizens for acquire British passports. So as many Irish people as possible, from the north and the south, may end up with two passports- just as thousands of eligible British citizens are scrambling to acquire Irish passports to facilitate automatic, visa-free entry to the EU.

My legal guidance confirms that indeed, Irish citizenship rights in GB will be subject to Brexit negotiation

What will be the rights of Irish citizens who live and work in Northern Ireland and regard themselves as native to NI? Will they be the same or different, internally and externally, as the rights of British citizens who live and work in Northern Ireland and who also regard themselves as native to NI?

Brexit will have no effect on those with dual citizenship in Northern Ireland or those born in Northern Ireland who have not previously claimed UK passports as they are automatically entitled to them. Individuals who were born in the Republic but who live in Northern Ireland will be in the same situation as those born in the Republic and living in any other part of the UK.

Under the Common Travel Area, currently those born in the Republic are treated entirely the same as UK passport holders under the Ireland Act 1949 and under different welfare provisions. However, this status may be subject to negotiation under Brexit with both Brussels and Dublin.

While both Governments have said they wish the status to remain the same, as Ireland is staying in the EU Brussels will also have a say in regard to those with UK passports wishing to live and work in the Republic. There is no specific ‘Northern Ireland’ status either for those born in the Republic or Britain living in Northern Ireland.

After Brexit both states wish to preserve the common travel area. Will any amended arrangements for common travel be different for people of either citizenship who are native to Northern Ireland? If so how? Would British and Irish citizens native to NI be treated differently entering and exiting GB and the Republic?

This will really be the subject of negotiation. While both governments have stated that they wish to keep the CTA and theoretically this may be possible whether or not the UK stays in the single market or joins the EEA will impact on the CTA. While travel for leisure may be relatively straightforward, goods or services crossing the border may be effected. The status of those from Northern Ireland crossing the border into the Republic or travelling to Britain may largely depend on the passport they hold. The most straightforward thing would be for an individual to hold both passports if they are entitled to them. If you hold an Irish passport you will remain an EU citizen while if you have a UK passport you will be entitled to travel freely within the UK. It is impossible at this point to be certain of the outcome as it will be part of the negotiations.