I say to the noble Lord, Lord Butler, that the financial convention has not stayed absolutely the same for 300 years. The convention was that this House did nothing about the Finance Bill or, indeed, other economic measures. In 2000, we set up an Economic Affairs Committee. The House of Commons went into free-fall about encroachment on financial privilege. In fact, we were told that Gordon Brown, the Prime Minister at the time—I see the noble Lord, Lord Lisvane, nodding—was incandescent at the idea that there should be a sub-committee looking at the Finance Bill. However, those things happened and the world did not collapse. Financial privilege and the right of the Commons to have the final say was not impeded.
To my mind, this is a matter of very high and clear-cut politics, and of highly nuanced constitutional significance. Overall, I believe that the most important power of this House, while leaving the last word to the other place, is to ask it to think again, and I urge the House to use that power this evening.