Yes, and that would be another one of those challenges, and again I'll come onto the Scottish experience there as well.

Just to round off what I was saying in relation to the higher bands, growth in revenues for those two bands does tend to be more volatile from year to year than basic rate revenues, and they do vary more between parts of the United Kingdom, and that does affect the year-to-year net budgetary impact of income tax devolution via the block grant adjustment mechanism.

So, to give an example and to turn to the Scottish experience, Scotland does have full devolution of income tax, except for income on savings and dividends, and what I'm going to say next is really important, because it does set out and demonstrate the real risk that is involved here and the real volatility, which is what we really do need to consider before determining which way forward would be right for us. 

So, the Scottish Fiscal Commission is expecting a net negative impact of around £100 million on the Scottish Government budget this year, and that is despite additional tax effort by Scottish taxpayers of around £850 million from the rate and threshold changes. I think that does demonstrate the level of risk that is taken on when we're looking at this. So, understanding the behavioural changes is key, and I'm looking to better understand the behavioural impact in relation to the changes that the Scottish Government have made.