The crown stamp had been used on pint glasses for more than 300 years to show they are large enough to hold a full pint.
An EU directive, which took effect in 2006, required the use of an EU-wide "CE" mark which stands for Conformité Européenne - French for "European Conformity". The mark appears on many other products, and it is used to show that they meet the EU's safety, health and environmental rules and can move freely across its countries with no additional checks.
As this helpful analysis from BBC Reality Check makes clear, the European Commission has rejected the idea that EU rules stopped the UK from having the crown stamp on glasses as well.
A spokesperson told the BBC: "EU law does not prevent markings from being placed on products, so long as it does not overlap or be confused with the CE mark."
Following Brexit, goods will now have to use the UKCA marking - "UK Conformity Assessed".
This claim from the UK government received widespread publicity. It was deeply misleading. This false claim is even more troubling than others because the Downing Street press office is staffed by civil servants who should remain politically impartial at all times.
We approached the Downing Street press office for comment, but received no reply.