But it is a highly relevant area of study for three reasons. The first is that many of the natural monopolies that were once state owned – power and water companies, for example – are now in private hands. The second is that there are some sectors which have grown in size and power in recent years, and where the risks to the public have become greater. Banking is one, with the big four – Barclays, HSBC, Lloyds Banking Group and RBS – dominating the UK high street.