We have all felt the strong feeling of panic when we are looking for hotels, flights etc and see on the website that there is "only 1 left". 

 Robert Cialdini in his book 'Influence: The Psychology of Persuasion' identified this technique as Scarcity. Simply stated the perception of something seems to become more attractive when its perceived availability is rather limited.

While  this technique, as well as the other 5 principles of persuasion are valid influencing tools, I am pleased to see UK regulators ensuring they are being deployed honestly.