Tweeeeenty five billion pounds! So screamed yesterday’s headlines after the Bank of England published an estimate for the capital shortfall of UK lenders. But does anyone understand what this number really means? And does it even matter if they don’t? Dispiritingly, the answer to both questions is probably no.

Investors may well ask why the BoE did not release its analysis of individual banks, as if to say: “We know who has a shortfall and you don’t. Nah, nah!” And the aggregate ￡25bn does not include capital-raising measures already in train. Even so, to put the number in some context, Barclays, Lloyds, Royal Bank of Scotland, HSBC and Standard Chartered currently have ￡300bn-odd of core tier one capital between them. Likewise, the latest assessment that banks have underestimated their assets adjusted for risk by ￡170bn compares with total risk-weighted assets across UK banks of more than ￡2.5tn.

Any calculation of risk-weighted assets is based on assumptions. Who is to say the BoE is any cleverer than the banks? The stress testing of loans to the eurozone and to UK commercial property is also based on pure guesswork. That said, if investors are worried about commercial property, they might want to know that RBS has 15 per cent of its loan book exposed to the sector. Commercial property makes up only 3 per cent of Barclay’s overall loan book, by contrast.