From the TV licensing website.
Part 4 of the Communications Act 2003 makes it an offence to install or use a television receiver to watch or record any television programmes as they're being shown on television without a valid TV Licence. The Act empowers the BBC to make and amend the terms and conditions of a licence. It allows the government to make regulations to exempt or reduce the licence fee for certain persons in certain circumstances. It also makes it an offence for anyone to have any television receiver in their possession or under their control who intends to install or use it in contravention of the main offence (above), or knows, or has reasonable grounds for believing, that another person intends to install or use a television receiver in contravention of the main offence.
The Communications (Television Licensing) Regulations 2004 define what is a 'television set' and who is a 'television dealer'. The regulations also set out the various types of TV Licence, the criteria for obtaining them, the fees payable for them (including the frequency and amount of instalments) and the different concessions available, including concessions for people who are blind or severely sight impaired, people who are over 74 years of age, people who live in residential care and people who run hotels, guesthouses or campsites.
The Wireless Telegraphy Act of 1967 (as amended) has been repealed meaning that from 25 June 2013 onwards, TV dealers are no longer required to notify TV Licensing when they sell or rent out TV equipment.
http://www.tvlicensing.co.uk/about/legislation-and-policy-AB9/