I looked up the forecasts for the revenues from self assessment Income Tax before my lecture last night.
In June 2010 the Budget forecast for this tax revenue for 2011-2014 was a very useful £85.9bn.
In the Autumn Statement 2012 the forecast for the same time period was just £66.7bn.
That’s £19.2 bn down, or a loss of 22.3%.
They got the growth rate of the economy wrong, and the underestimated the way higher rates depress revenues.