Call it the regulatory ratchet. Now that Lloyds Banking Group and Royal Bank of Scotland have insured their balance sheets, attention is swinging back to Barclays. It looks relatively light, capital-wise. Whereas Lloyds and RBS will soon have core tier one capital of 14.5 per cent and 12.4 per cent respectively, Barclays had pro forma core tier one of just 6.7 per cent at the end of 2008. Given that even HSBC has launched a $17.7bn rights issue that will lift its core tier one ratio to 8.5 per cent, Barclays looks isolated.

The UK taxpayer can only blanch at the prospect of another bank with a super-size balance sheet coming to God. In the past fortnight, the UK has swallowed contingent liabilities of almost £600bn – 45 per cent of UK gross domestic product. It is hard to know how much of Barclays’ £2,053bn balance sheet might end up in the same government asset protection scheme. Negotiations have barely started. But it is unlikely to be as high a proportion of assets as at Lloyds or RBS, which have hived off the vast bulk of the risk relating respectively to 24 per cent and 15 per cent of their balance sheets.