For every £1000 generated with UK GDP the government taxes, borrows and spends £401 of it very inefficiently and badly which gave them a budget in 2017-18 of £814,000,000,000. This budget has risen every year since 2002. With 32,080,000 in work this works out at an average tax of £25,374 per working person. Now our progressive tax system means that higher earns pay far more of their income as tax and get less free stuff, so the government makes a profit here on the basis that they can steal more of your income without you starving or sleeping on park benches. Conversely, the lower earners pay little of no tax and get more free stuff and are subsidized.
The top income tax rate of 45% (total minimum possible tax with extras is actually a minimum of 49.375% plus 20% VAT if you spend it on anything 39.5% is the most spending power left from your economic output at the highest tax levels, there are other ways like being an employee that make your spending power much less than this). 45% tax rate brings less revenue into the Chancellor than the 40% used to where it is the wrong side of the Laffer curve and the old 50% less still.
ALL areas of taxation (except possibly VAT and Council Tax) are now the wrong side of the Laffer curve, so virtually ANY tax rate you now increase will bring in less revenue which is why all UK political parties are looking for new ways to pluck more feathers from the goose. Liebour massively increased public spend and UK debt levels with virtually no increase in output from the public sector where the majority went on subsidies, more non-jobs, overmanning and increased public sector wages which is what the Unions with their positive feedback loop sponsoring them pays them to do and why Liebour governments normally fall when the money tree contains no more leaves or fruit.
https://www.ukpublicspending.co.uk/government_expenditure.html