Probably the best think to do is google "income tax tipping point." The issue is that the real high earners can usually arrange their affairs to avoid UK taxes, but people on lower incomes cannot.
We can even learn from the defeated Labor govt in Oz, who increased the "tax free" ceiling to $18,000 before you pay tax.
Whilst we all accept the need to pay taxes, taxes need to be seen to be fair, otherwise ultimately there is trouble. Poll Tax failed because even the people who benefited from it thought it was unfair, so Mrs Thatchers Conservatives lost the Eastbourne by election sending panic amongst her MPs, who booted her out. Her downfall had little to do with "Europe," Heseltine, Hurd, and John Major didn't really offer much change in European policy, but they all promised to repeal Poll Tax.
In the early 1980s, with high tax rates, the top 10% paid 10% of the total income tax take. Once Geoffrey Howe cut the top rate to 40% this soared to 25%, leaving a smaller bill for us mere mortals.
You can do any amount of research on this topic, and look in popular culture; remember the Rolling Stones and "Exile on Main Street," they had to leave the UK to avoid taxes, Ian Botham lived in the Channel Islands for a year when he had written a book, even in the 1960s, Jim Clark, and Jackie Stewart moved abroad to avoid UK taxes, more recently Lewis Hamilton did the same.
Sorry I cannot give you a simple link, but if you do some digging you, like I was, will be surprised to see cutting top earners taxes actually benefits poor people.
You could also make a case for abolishing NIC, as it is levied disproportionately on lower salaries, I think it is 12% up to £40,000 then it reduces to 1%, I think.