Having read through The Consumer Protection from Unfair Trading Regulations 2008m this is covered under Schedule 1, section 5:
5. Making an invitation to purchase products at a specified price without disclosing the existence
of any reasonable grounds the trader may have for believing that he will not be able to offer for
supply, or to procure another trader to supply, those products or equivalent products at that price
for a period that is, and in quantities that are, reasonable having regard to the product, the scale of
advertising of the product and the price offered (bait advertising).