Thanks for allowing me to expand on that a little bit. I'm not advocating one or the other, but probably a combination of the two. The reason my brief focused on the tax is that I had a good example of a levy having worked really well in the United Kingdom without having exactly those kinds of costs going back to the consumer. Those taxes or levies were actually financially neutral, because it was reinvested.
The other point is that I completely endorse any idea of reducing our emissions by investing in technology. But again, we have to get around the idea of intensity-based cuts; we need absolute cuts in carbon. I just want to correct that: any combination, as long as we really value the carbon at $30 a tonne.