That's bullshit! The UK Isn't the place where rich ppl are worse off, and then leave because of it.
Just for comparison, in Belgium:
0 to €15,200 25%
€15,200 to €26,830 40%
€26,830 to €46,440 45%
In excess of €46,440 50%
Income tax in Spain:
€0 €12,450 19%
€12,450 €20,200 24%
€20,200 €35,200 30%
€35,200 €60,000 37%
€60,000 and above 45%
Income tax in England:
Up to £12,570 0%
£12,571 to £50,270 20%
£50,271 to £125,140 40%
over £125,140 45%
So even when you do the £/€ conversion, you can see that the UK isn't worse off income tax wise. Most of Europe (yes I know I only put 2 other examples, but hey) have much lower thresholds for higher tax.