Inland Revenue figures confirm what this site has been saying for some years. To collect tax from the rich you need to set a competitive tax rate. That helps you offer Income tax cuts to everyone else.
In the last year of Labour when the rate of Income tax for the rich was 40% the top 1% of earners earned 13.9% of all the income in the country. They paid 26.5% of the total Income Tax.
The advent of the 50% tax rate led to a predictable decline in the numbers of rich staying and paying, and to lower incomes. Their share of total income fell to under 12%. Self assessment tax receipts fell. With the reduction of the top tax rate to 45% the top 1% have got back up to near their 2009-10 position, earning 13.7% of total income and now contributing a record 29.8% of the total income tax. (HMRC estimated figures for 2013-14) Both the amount paid and the proportion of total tax would doubtless be higher if the top rate was back to Labour’s 40% rate.