There are so many companies that manufacture burglar alarms. The most recommended and approved by the UK government are ADT systems, AGS systems and British gas home security.

ADT systems
They are the leading provider of electronic fire and security services in the whole United Kingdom. They specialize in home security, and commercial security including, electronic article surveillance (EAS), fire detection, alarm systems, gaseous extinguishing and asset tracking solutions to a wide range of people and organizations. They protect 89 out of the UK