Further to Heathfield's answer:
The 2003 Licensing Act effectively means that a local authority must grant a licence, for whatever hours are asked for, unless they're aware of a valid reason not to do so. The Copdock Mill Tesco, on the edge of Ipswich, applied for a 24-hour licence as soon as the provisions of the Act were due to come into force, and were granted one with no problems. Other supermarkets around here initially applied for more restricted hours (perhaps because they were aware of some possible local opposition to 'full' licensing), resulting in some strange anomalies. For example the Stowmarket Tesco was open until midnight but only licensed for the sale of alcohol until 11.00pm. However they've now applied for, and been granted, a licence covering all of their opening hours.
Chris