SW20 drivers lock replacement - How to get the latch off the door handle!?

Hi folks,
 
Can anyone please help advise how the heck I get the door lock disconnected from the door handle?  I want to fix my central locking before Queensland! :)
 
More info and images:
I'm replacing the door locking mechanism (not the key barrel, the unit that holds the door shut) because my previous one has lost it's ability to lock electronically (remote lock/unlock can't push the lock far enough any more).
 
I have followed the BGB (images attached - the bit circled in red is what I'm trying to disconnect) and disconnected everything but for the life of me cannot get the metal lever to door handle disconnected - the one that connects to the outside door handle and opens the door.
 
BGB just says move the plastic bit aside and pull it out.  I can half move the plastic bit, and while I know the metal lever has an indentation on it that is designed to keep it in place, I cannot wiggle it out of the handle.  
 
It doesn't help that it's pretty tight to get to through the door access holes.
 
What do I do - disconnect the handle and then with the better access, remove it that way?
 
Thank you very much
 
Firthy
 

So squeeze the plastic bit together and try to push the lot through? I thought I might have had to pull the plastic apart to let the metal slide out of it.

I actually think someone previously put the plastic tab the wrong way around so when I try to release it it doesn't do it. Thanks Andrew I'll try.

Ahh you're a star. Thanks mate I'll see how i go