Earlier quoted context omitted.
60% of what exactly? Take home pay for a salary of £100k is about £66k, and about £74k for £120k.
60% of the amount between £100-120k. For that additional £20k in gross salary, your take home pay only increases by £8k, so the _marginal rate_ for each additional pound in that bracket is 60%.
If you go up to 200k USD compared to 150k GBP, then you get to keep about 66% of it in California and about 60% in the UK. That's a difference that's quite easily lost in the noise when you consider differences in overall cost of living, healthcare, etc. etc.
I've found that Americans have a very fixed perception of America having low taxes and Europe having high taxes. But taxes in the UK are really not that much higher (except VAT in comparison to sales tax).