From my understanding of the law goods can only be described as 'discounted' if the original price was charged for 14 days or more.
I can't be arsed to check but I would bet that a number of retailers deliberately inflate the prices of some goods at the start of November. They can then offer 'massive discounts' as the goods have been on sale at the higher price for the required period.
There does seem to be a psychological blind spot that a lot of people have where the money 'saved' is more important than the money spent. Spending £300 on a TV discounted from £800 is not saving £500, it's spending £300 unless you were going to buy that TV anyway.