Windows need as much protection as doors. Fit at least two locks on an opening window, spaced across the frame so that it is difficult to lever open. Throw away any short screws included with the lock and replace with longer screws with a clutch head. A clutch-head screw has bevelled slots so the screwdriver can drive the screw into the wood but will slip out of the head when trying to undo the screw. They are available from hardware shops. Key-operated locks are the best option, preferably those that lock automatically when shut. To deter burglars, the locks should be large enough to be easily seen. As a final check, push hard on the frame from inside - add a lock wherever it gives.

Casement Windows

Use snap-shut locks on wooden casement windows. Fit these on the frame, adjacent to the opening window - usually on the sides. They don't need a key to close so are convenient to use.

Surface-mounted locks are good for securing metal casement windows. They come with self-tapping screws and should be fitted near the centre of the opening edge of the windows. Mark the position of the screws with a bradawl and drill pilot holes with a high-speed steel twist bit. Screw the lock in place.

Metal stays (the long arms that clip over small pegs fitted to the window frame) on casement windows can be reinforced with stay locks so the window can be locked partially open for ventilation. These are small metal locks that fit over the pegs. The upright post is threaded. Once the stay is hooked over the post, small locking pieces are threaded over the top and locked.

Sash Windows

Protect sash windows with screw-through bolts. Drill holes through the top of the bottom sash and the bottom of the top sash, and insert the brass barrels. The bolt that holds the two sashes together is screwed tight with a key.

As a temporary measure, you could simply screw two long woodscrews through the overlapping horizontal parts of the sash frames so that they are fixed together and the window cannot be opened.

For sashes that you open regularly, it may be worth fitting sash stops on the window frame. These allow the window to be left slightly open for ventilation. Hold the faceplate to the bottom of the top sash and mark where the bolt will shoot through. Removing the faceplate, drill a hole for the bolt. Screw the faceplate over the hole, then screw the protective plate in place on the top edge of the bottom sash.