Professor John FitzGerald:

I do not want to go there. In the black market my suspicion would be that there is, as in most economies, but I do not know they are making a huge amount of money. When I think about the people I come across who might not be declaring for tax and what I am paying them and multiplied by the number of hours they would want very hard to make an awful lot of money outside the tax net. My suspicion is that it is the allowances which people on high incomes have - they are doing it legitimately - that need to be looked at.