Also even the safe job wage in the UK is perhaps only 2/3 of in Germany for example
Not sure if it's true so let's look at some stats: Germany median for software engineer: €66,000 United kingdom median: €58,000
Note depending on source, these numbers both vary broadly within the same range, but with Germany salaries being about 10-15% higher on most sources, so nowhere near the figure claimed.
EDIT: Please don't downvote me for admitting a mistake
33% less equates to them earning roughly 50% more. The difference between 10-15% and 50% is huge!
(trivial example, if someone is earning £100,000, then someone earning 33% less makes £66,666. But Someone earning £100,000 makes 50% more than someone making £66,666)