The number of people holding wheelclamping licences has increased since the Government consulted on ways to control the industry earlier this year, according to the RAC Foundation.
Figures show there are 2,100 individuals licensed to clamp - a rise from 1,200 in March 2008 and 1,900 in April 2009, when the Home Office launched its vehicle immobilisation consultation.
RAC Foundation director Professor Stephen Glaister said: "There will be little festive cheer for bargain hunters if they put a wheel wrong when it comes to parking.
"The figures reveal more and more people are becoming clampers because the business is so lucrative and the law surrounding it so lax."
He added: "With charges for being clamped and towed often running into several hundred pounds, cowboy clampers will be out in force during the Christmas sales, on the lookout for motorists who leave their car in the wrong place even for a few minutes.
"The huge rise in licence holders proves the Government needs to act quickly. It has promised a cap on fees, an appeals service and a binding code of conduct. In 2010 it needs to deliver."
The RAC Foundation urged drivers to be extra careful over the festive period and to check parking arrangements before they head for the shops, and to consider options like park-and-ride schemes.