Does your home or conservatory have patio doors that look like French doors?
These ones are considered safer than the sliding ones as many people know.
Please check the hinges of yours.
There normally is a pin which drops down the hinge on which the door opens and shuts.
This pin is placed in by gravity but there is a tiny screw which pierces this pin at a 90 degree angle which keeps this pin from being removed.
If this pin is not there, or is in loosely, it takes a thief no time at all to remove the pin and remove your door.
PLEASE CHECK this pin and screw or get someone to do it for you.
A nieghbour of mine got robbed yesterday in this fashion. The houses on our estate are no more than 3 yrs old and all have these types of doors installed. Of about 12 properties checked, all of these screws were loose except ours.