My mother (South African) recently travelled to visit me in Northern Ireland and arrived in Dublin with her UK visa in her passport, as she has done 12 times before. She was given great trouble at immigration in Dublin airport and threatened with being sent back.
She was alone and in a wheelchair and eventually allowed entry with a warning to never do this again! She has previously traveled the same route many times with no problem. She was also told she had to activate her visa for the UK...
She was going to travel by car from Dublin to Northern Ireland, and with no hard border between NI and ROI she wouldn't have come into contact with any UK immigration.
Just wondering if anyone else has had the same issue recently?