Dual British nationals have been warned they may be denied boarding a flight, ferry or train to the UK after February 25, 2026, unless they carry a valid British passport.

The warning by the Home Office comes amid scores of complaints from British people living or travelling abroad who have suddenly found themselves at risk of not being allowed into the UK.

The problem has arisen because of a change in border controls, when everyone travelling to the UK will need permission to travel, unless they are a British or Irish citizen or are otherwise exempt. Visitors for short stays must apply for an Electronic Travel Authorisation that costs Ksh218.

But dual nationals will, for the first time, be obliged to show their British passport to travel to the UK or pay what many believe is a punitive price of about Ksh103, 000 for a “certificate of entitlement” to attach to their second nationality passport to board a flight, ferry or train.

One British woman living in Germany for years, who has dual nationality, said she feared her children were going to be affected by the changes, particularly her son, who is due to travel to the UK in four weeks.

“I’m really annoyed about being treated as Brexit collateral once again with this short-notice, shortsighted, arbitrary change of the rules,” she said.

While the government introduced the rules last year, she and many others feel they had not been communicated well to those living abroad and that keeping up two passports for a family is an expensive “luxury” that not everyone can afford.

One British woman living in Spain for more than 30 years chose to take out Spanish citizenship because of Brexit, and up to now was free to go to and from the UK with her Spanish passport.

But Spain requires non-nationals naturalising to renounce their previous nationality, and presenting their British passport at the airport will legally risk their Spanish nationality.

She said she is aware that many will argue she should not have renounced her British passport, but that this change of rules will apply to many children of British citizens born in Spain who have never held a British passport but whose records will show dual nationality at border control.

“It seems a strange anomaly that while the UK is willing to recognise dual nationality, it refuses to recognise that a valid EU passport held by a UK citizen can give the right of entry to the UK,” said Julie, who asked that her real name not be used.