With the opening up of the last few areas in Britain to full competition, all the country's 26 million electricity and gas customers now have the right to shop around for their supplies. It also means the UK becomes the first country in the world to offer all customers a choice of energy supplier. At the end of May, the gradual phasing in of competition for domestic consumers was completed. Already, 1.5 million electricity customers have opted for a different supplier and are switching at a rate of 100,000 a week. So far, energy regulator Callum McCarthy has mainly emphasised the financial benefits to customers in switching suppliers, but an increasing number of "green" tariffs offer customers control over the quality of their electricity supply.