Let us be plain. The fact that housing is unaffordable for large numbers of first-time buyers in large tracts of the country is not the fault of the mortgage industry. Constraints on the supply of new housing are mostly to blame, not a shortage of home loans, nor some kind of conspiracy to deny borrowers the terms they want.

But it is convenient for ministers to suggest that the financial services industry could be doing more, hence Gordon Brown’s promise to introduce measures to stimulate supplies of long-term fixed-rate mortgages.

His reforms could help at the margin. Sweetening the capital adequacy rules on covered bonds, the financing instruments used by mortgage providers to finance long-term fixed-rate loans, makes sense. If the Debt Management Office (DMO) could issue instruments helpful to lenders, that would be good too, so long as tomorrow’s taxpayers are not disadvantaged. The DMO’s job is to borrow for the Government at the keenest possible rates without distraction. Relaxing rules for building societies to give them more access to the wholesale markets might occasionally help.

But all these measures are marginal. The reason long-term fixes are not popular with borrowers or lenders is that they are expensive, and there is a very good reason why: the lender, or a counter-party to the lender, is being asked to take a huge bet on inflation remaining quiescent for a quarter of a century, hardly the surest wager given Britain’s record.

Short of an explicit government subsidy, they will always be more expensive than variable rate loans over the full cycle. They may suit some homebuyers who are low paid but with good job security, but they are no panacea.

patrick.hosking@thetimes.co.uk

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