The appearance of the EU symbol dates back to Council Regulation (EC) No 2411/98 in 1998. The blue stripe has to be between 40mm and 50mm wide. The centres of the 12 stars have to be arranged in a circle of radius 15mm with the tips of the stars 4-5mm apart.
If you don't have a national identifier on your numberplate, the alternative is the good old-fashioned oval sticker.
The sticker goes on the rear of the vehicle. If you rely on numberplates, the identifier has to go on the front and on the back.
Vehicles registered in EU member states with numberplates in the common EU format are allowed to travel freely within the European Economic Area.
This was fine while we were still in the EU, and indeed fine during the transition period following Brexit, but that all changed on 1st January 2021. Since then a national flag has to be displayed instead of the EU flag when travelling abroad (and new numberplates can no longer be manufactured with an EU flag on them).
I found these GB/flag combos on cars registered between 2011 and 2020, which makes me think displaying the Union flag has been legal long before everyone got het up about a referendum.
And the national flag doesn't have to be the Union flag, it can also be the Cross of St George, the Cross of St Andrew or the Red Dragon of Wales.
You might expect the Cross of St George to be particularly popular with drivers of a certain mindset, but in my perambulations it's telling that I spotted a saltire and a dragon long before I spotted a red cross.
The flag must always come above the national identifier.
The next change came on 28th September 2021 when the government changed our national identifier from GB to UK.
Allegedly they did it to better represent Northern Ireland within the union, because it was a bit galling for those who weren't officially part of Great Britain to have to display GB on their vehicles. There may also have been an element of "because we now can", although technically we could have changed from GB to UK at any time over the last 100 years.
UK numberplates are a lot harder to spot than GB numberplates because they've only been required for the last 15 weeks.
The top example shows a brand new car with a Union flag and UK imprinted on its numberplate. The bottom example shows a car registered in 2008 which has been upgraded via a sticker. Stickers are a perfectly legal way to update to the current format.
These national identifiers are only relevant if you choose to take your car abroad, which very few Britons have done in the last year. That explains why GB is still much more common than UK on British numberplates (and why having no identifier is even more common... because most cars never go overseas).
In good news it's not illegal to display GB on your numberplate otherwise the owners of millions of vehicles would have found themselves breaking the law overnight. Indeed the government permits a surprisingly broad range of national identifiers, as follows...
• UNITED KINGDOM, United Kingdom or UK
• GREAT BRITAIN, Great Britain or GB
• CYMRU, Cymru, CYM or Cym
• ENGLAND, England, ENG, Eng
• SCOTLAND, Scotland, SCO or Sco
• WALES or Wales
But you can only display these alternative identifiers if your vehicle stays within the United Kingdom and Ireland. Head abroad to the EU and the only acceptable combination on your numberplate is now the Union flag and UK. Better get a sticker next time you travel.
The green bands can be blank or combined with a national flag option and country identifier. I haven't seen a non-blank one yet, but I guess electric vehicles don't go abroad as often as petrol/diesel vehicles. Also green bands remain optional rather than mandatory, so only owners wishing to parade their eco-credentials will have one.
So it's very much been all change at the start of numberplates over the course of the last year. At the end of 2020 they typically displayed GB and an EU symbol but now it's UK and a national identifier, plus maybe a green band if tailpipe emissions are zero. Who says this government isn't getting things done?