[Denver]

As any Brit knows, when it comes to UK passports, deep red is the colour of choice.

It also happens to be the most common passport colour with all members of the European Union, apart from Croatia, sporting a burgundy hue.

The Economist called this a "branding exercise" - though there's no word on whether we'll stay a nice shade of EU red once we've left it.

It's not just EU states either. The Andean Community (also known for past EU-ambitions) of Bolivia, Colombia, Ecuador, and Peru also has burgundy passports.

Switzerland matches its passport colour to its bright, red flag.