Professor John McHale:

There is no doubt that public investment is linked to growth. These are the trade-offs we face. There is value to current spending and value to capital spending. They have to be traded off. Often, the effects of cutting capital spending are more long term but they affect growth. However, they are the more likely cuts than those which result in pain being felt more in the short term - these are more often on the current spending side.

We need to think about ways in which we can avoid that. We need to ensure that we do not have too low a level of capital spending, given its importance to long-term growth. That is behind the proposal to focus on the public investment ratio, although we are also facing an overall deficit target.

I would not term it a proposal or a trick. It is simply that we need to focus on that question.