The UK Patent Office published some clarifications what would happen with all European trademarks in case of a hard Brexit without a deal with the EU.
In that case, The UK will recognize all registered EU trademarks and will transform them into national trademarks. They will be indicated with UK009 in front of their EU numbers.
There will be no cost for the relevant owners and as little administrative burden as possible. However, the Patent Office will not issue trademark certifications for them. Information for these marks will be available in the UK trademark database.
When it comes to EU applications for trademarks, their owners will have up to 9 months to file identical applications in The UK. In that scenario, they will use the same priority date from their EU applications.
The full text can be found here.