First, an assessment has been made and the figures in the Red Book take account of anticipated behavioural changes. I noticed that the Institute for Fiscal Studies described those assumptions as being not unreasonable; they are sensible assessments of the kind of changes that will be required.
However, I would caution my hon. Friend on one point. Sometimes there is a suggestion in these discussions that, in reality, we cannot increase the tax paid by people on high incomes. That is not the point that he made, but it is sometimes suggested that, if there is to be fiscal consolidation, the practical reality is that the additional contributions have to come from those on lower incomes. That is not his position, or my position, but I think that it is very important that we resist that view and that we proceed with measures such as this one, which require, as I have already set out, an additional contribution in tax from the 2 per cent. of highest earners in the country.