How Do I remove old Lock barrell from UPVC door?

Hi the lock in my upvc door is broken , so i was going to remove it to replace it . I have removed all the door handle and all the locking mechanism down the side of the door and cant see how to get the lock barrell out? any ideas ?
mark@crazycucumber.com, January 2006
There is a screw in the side of the door that needs to be taken out , near the door latch . then put the key in the barrel and turn it until you can pull the barrel straight out. thats it !

Zoe, January 2006