The country has been left divided over the colour of the new post-Brexit passport.
Earlier this week, the Home Office’s official Twitter account posted a video displaying the new travel document.
It captioned the tweet, “Britons will once again be able to travel with a blue passport when the iconic colour returns for the first time in almost 30 years.”
The video - which has attracted 3.3 million views so far - has left many people baffled, claiming the colour of the cover appears to be black, or even green.
Social media left divided
One Twitter user wrote, “There is some right Emperor's New Clothes going on with this 'blue' passport that actually looks black.”
There is some right Emperors New Clothes going on with this 'blue' passport that actually looks black https://t.co/Nb4eRJkz0I
— Smith (@AnotherSmith909) March 2, 2020
Another wrote, "People. It's black. Not blue."
And one adamant Twitter user commented, "The new passport is not blue or black, it is green. Do not engage in rigorous debate with me on this because I literally do not care what you think, you are colour blind."
The new passport is not blue or black it is green. Do not engage in rigorous debate with me on this because i literally do not care what you think you are colour blind (especially you Stuart)
— em 🦒 (@182reasons) March 5, 2020
Meanwhile one person wrote, "When we had the passports before they were black. And now they're black again. We've literally never had blue passports!"
This is like that dress thing again. When we had the passports before they were black. And now they're black again. We've literally never had blue passports! Can someone let me in on the bizarre naming convention? #BluePassport #NotBluePassport#BlackPassport pic.twitter.com/6IZ6XDJPyO
— Michael Birtwhistle (@SalfordMH) March 2, 2020
Colour expert advice
"I'd say it's black," Stephen Westland, professor of colour science and technology at the University of Leeds told the BBC.
"If most people looked at this, they'd say it's black."
But, he says, describing colours in terms of names can be imprecise, and individuals will have their own different perspectives. If enough blue is added to black, Westland advises that there will be a transition point when people will begin to see the colour as blue.
"But that point varies for different people," he explained.
This means that some might see a colour as an extremely dark shade of blue, while others would see it as black.
Home Secretary Priti Patel has said the return to this "iconic blue" was "entwined with our national identity and I cannot wait to travel on one".
The Home Office would not specify the shade of this blue, although a spokesman said it was close to, if not exactly, a blue numbered as 5395C in the Pantone classification.
New passports to be issued the end of the month
The new blue passports will be sent out at the end of March, but leftover burgundy stock will be used as a priority to get rid of them. The old ones are set to be phased out by the end of this year.
British passports were dark blue from the inception of the old design in 1920, until 1988, when they were changed to burgundy, in line with most EU passports.