"most European legal systems" implies more than one system, they're most likely referring to the "European Union" and not the geographical continent of Europe, which the UK is not a part of anymore
Generous interpretation.
Also, UK law was always very different from Continental legal systems, Brexit or no Brexit. I don't think any country on the continent has common law, relying on precedent more than on statute.
My bad, I misread the thread, edited my comment to a no-op
The UK is famously no longer a part of the EU.
EU membership has nothing to do with being physically located in Europe.
The UK, Switzerland, and most of the former Yugoslavian states are not in the EU. Same for Iceland.
But one European countries legal system also doesn’t constitute “most European legal systems”.