Many of the 1m Britons living in the other 27 countries are in Spain

Up to 260,000 British nationals living in the EU — many of them pensioners — are expected to return to Britain if there is a no-deal Brexit, placing a huge burden on the NHS and other services.

Boris Johnson’s no-deal war cabinet was told last week that “gaps” would open in the healthcare provided to British citizens living in the other 27 member states in the event of no-deal and that healthcare was the “most immediate risk” facing them.

Ministers have been told that reciprocal healthcare arrangements will cease and “state pensioners” could “become vulnerable” if they could not access treatment in the EU, which is now paid for by the British government. Changes in how expats access healthcare would lead to between 160,000 and