Figures released today by the Council of Mortgage Lenders (CML) and the Building Societies Association (BSA) are perplexingly different. On the one hand, the CML says that gross mortgage lending rose 13 per cent last month compared to July 2006. On the other, the BSA says gross lending was down by nearly 9 per cent from last year.

The BSA and CML are showing slightly different pictures. The BSA only reports mortgage lending from building societies, whereas the CML shows mortgage lending from banks as well as building societies.

The discrepancy does not stop there. The alarming figure from the BSA is that net advances, the total value of mortgage loans given to borrowers less the sums paid off, are down by 64 per cent. Unhelpfully, the CML does not provide a net advances figure.

There is one powerful reason why this might be a monthly blip rather than the beginning of the demise of the building society sector.

Two of the biggest building societies are gearing up to merge in a matter of days: Nationwide will amalgamate with Portman on August 28. Mortgage brokers say that Portman, usually one of the most competitive lenders on the market, has recently become less aggressive in terms of its mortgage deals on offer.

And while these lenders concentrate on in-house matters, some of the bigger banks have stepped up their efforts to capture a bigger slice of the market. Halifax is currently offering market-topping rates after revealing in June that its share of net new mortgage lending had more than halved to 7 per cent. Likewise, Abbey seems determined to up the ante, with Alliance & Leicester also having become more competitive.

How long such behaviour lasts is open to question. But it suggests that followers of home loan data should pay greater heed to the CML than the BSA for now.

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