My Lords, I think I should allow the noble and learned Lord, Lord Davidson of Glen Clova, to continue; he seems to have made the points in a way that I could not hope to match. I suppose I should do more than say that I agree with everything that he said and sit down.
I do not want to reopen all the discussions that we had in the previous Committee session but it is important to recognise that, as the noble and learned Lord said, there is an appropriate series of checks on both sides before any power could be devolved under Clause 28. I remind my noble friend that a similar power exists under Section 30 of the Scotland Act. I see the noble Lord, Lord Sewel, nodding. A power already exists for the Scottish Government to request new powers, including on taxation, under Section 30 of the Scotland Act. Perhaps I should not have gone into this territory, but it provides important background to this matter.
My other point is that Scottish Ministers referred to the Section 30 power when seeking legislative responsibility for a whole range of things, from firearms to consumer protection. As noble Lords will know, in each case the Government rejected the requests made by the Scottish Government. As background to this discussion about air passenger duty, it is important to remind ourselves that there are proportionate powers under Clause 28.