The Natural Gas Retail Market has been open to full competition since 1st July 2007. Competition began in 2004 with three suppliers competing for the larger industrial and commercial customers. Since then through active consultation with industry participants and the development of new market processes the number of suppliers has increased (there were 8 suppliers as of 1st January 2011) with competition increasing in all sectors of the retail market. This has in part been enabled due to the ease with which customers can switch supplier. All natural gas customers are eligible to switch supplier since July 2007.
Details and reports on competition in the retail market can be found here