The trade body says the figures for January are the lowest total since February 2000, when gross lending was £7.9bn, and the lowest January total since 2000, when lending fell to £7.4bn.
The larger than average drop, says the CML, was due to mortgage activity being boosted by those wishing to complete their purchases before the temporary lift in the stamp duty threshold ended at the end of last year.
The threshold came back down from £175,000 to £125,000 at the start of 2010.
CML economist Paul Samter says: “We remain in a period of uncertainty for the housing market and economy at large. The market certainly improved over the second half of last year and started 2010 in better shape than most would have predicted twelve months ago.
“More recent developments have been influenced by the end of the stamp duty holiday, and are likely to foreshadow a larger than usual seasonal drop off in activity in the early part of this year.
“However, the Bank of England is likely to keep rates low which should continue to mitigate mortgage payment problems and help cushion borrowers from the worst of the recession.”