Finance (No. 3) Bill

I take it the right hon. Gentleman is not unhappy that tax levels are sensitive to profit, and I think that is perfectly reasonable, but why does he think that Ministers fail to understand that investment decisions are sensitive to tax, and why does he think Ministers fail to understand, notwithstanding the spot price, that the cost of extraction varies depending on the depth of the water, where we are in the North sea and even the type of oil that is being brought up?