The sales start on Boxing Day -- 26th December, and continue to the month of January, but the keenest bargain hunters get there early to be first through the doors.
In Oxford Street, queues formed outside shops ahead of predawn openings for the start of their sales.
At Brent Cross, in north London, more than 1,000 people were queuing at 3:30 am for the 'Next' clothing store's sale which began at 4:00 am.
Some people even camped outside the shops to be first in the line.
Some people are taking their friends shopping with them, and buying their Christmas presents in the sale -- a practical nut unromantic way of making sure you get the gift you really want.
For a less exciting but less stressful shopping experience, online retailers are also getting in on the act with January sales on their own.
The most organised of all are those who are already doing their present shopping for next Christmas, in the January sales.