1. Countries whose citizens say they are proud of their country (as measured by the International Social Survey Programme) are likely to have smaller black economies than countries with less patriotism. The US, Australia, Ireland and Canada, for example, have high patriotism and small black economies. Korea and Russia have unpatriotic people and large black economies. The causality here, though, might run either way.
2. Within countries, patriotic individuals are more likely to say that it is very important not to evade taxes. Patriotism is as powerful an influence in increasing - expressed! - tax compliance as not being self-employed or being a Protestant (Catholics are less fastidious about paying tax).
There are three implications here.
First, Boris might be right to call the 50p tax “an assault on London.” Londoners are, I suspect, less patriotic than the rest of us: it’s hard to love your country if you live in such a dump. So they are more likely to run away from higher taxes.
Second, if a government wants to get people to pay tax, it should think about ways of making us love our country more. Edmund Burke pointed out the best way to do this; “to make us love our country, our country ought to be lovely” (par 130 here).
Thirdly, there’s a slight embarrassment here for the conventional Left. Parts of it have traditionally been uncomfortable with patriotism, partly for decent reasons. However, this might be one force for achieving a Leftist aim of getting the rich to pay more tax.