The widening income gap between the very top earners and the rest of the population is increasingly reflected in the tax take. The share of income tax paid by the top 1% of taxpayers in 1979 was 11%, by 2011/12 this had risen to 27.5%. The income tax paid by the top 300,000 taxpayers accounts for 7.5% of all tax revenues.
For more information and a consideration of the policy risks on the tax side, see the Green Budget https://tinyurl.com/pwhakdn