Can you fit a lock to a double glazed window?

[alismossie]

I have just bought a house with 'old' double glazed windows - the kind with metal frames (not the white pvc kind). Th ere is no lock on these but the insurance policy I have taken out insists on locks on all windows. It is possible to fit locks on this kind of window?

[robber1]

There is a lock which screws to the frame. A handle swivels round and goes across the adjacent frame. It is locked into place with a key. The window cannot be prised open and if the window is broken it cannot be opened because of the lock. B&Q should have these. You may require 2 per opener depending how large the window is.