Yale Sash Window Locks in a Pack of 6 At Door furniture direct we sell high quality products at great value including Packet of 6 Yale Sash Window Locks in our Window Security range. We also offer free delivery when you spend over GBP50. http://www.MightGet.com/january-2017-12/yale-sash-window-locks-in-a-pack-of-6.asp
Idea: On first floor install 2 inch door latches on the window frame for security. Works as a window stop and no one can lift windows higher than the latch. Just retract to open the window all the way.