The police are asking all home owners with sash windows, particularly basement sash windows, to ensure suitable locks are installed. They have also suggested to install and display window alarms. One particular alarm that has been recommend is the GHB Window Alarm which can easily be purchased via amazon and is very affordable. See link here.
The more obstacles for a burglar, the more likely they are to leave your home alone.
ATA Security / Police Liaison
Non Emergency dial 101
Greenwich Safer Neighbourhood Team: 020 8284 5494 (not 24 hour)