However, the UK was not a member of the Schengen Agreement.
Now some EU countries in the Schengen Area, including Portugal, are insisting that passports must be no more than 10 years old, which includes the three month expiry buffer.
The Foreign, Commonwealth and Development Office told the BBC that the advice published on its website has, for several years, warned travellers they may face problems if they have a passport that lasts longer than 10 years.
However, John called the advice “incredibly vague”.