But they are largely taxed and regulated (to the degree they were regulated) abroad, in their corporate domiciles.

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British politicians, for instance, sometimes talk about scrapping their country's rule on resident non-domiciles because it allows wealthy people domiciled abroad, often in tax havens, to live in Britain tax-free.

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But, in theory, Barclays, Standard Chartered and HSBC have the option of paying a lower amount by moving their respective domiciles, their homes, offshore (to be clear, they'd still have to pay a fair whack, because they would still have taxable debt in the UK).

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Which, of course, does not absolve the government from responsibility for writing tax rules in such a way as to prevent companies paying significantly less than the official corporation tax rate - which, of course, is not easy in a globalised world where businesses can move their domiciles and can shunt revenues more or less wherever they choose.

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