First of all many thanks to the forum member who posted instructions on how to remove a door card when the dead lock is jammed on. I was getting a tad bored with climbing in the passenger door The lock loom connector was full of water as predicted. What a cr*p design! Switch cleaner and vaseline seems to cure it.

However though the deadlock now works the central locking motor on this door is not working. So I need to remove the lock which according to the Haynes manual means that I need to remove the lock barrel. But, and this is the reason for my post, the concealed locking screw does not appear to take an allen key as the manual suggests. Judicious use of blue-tac on a stick suggests it is a socket screw with 12 sides with a diameter of 3.8 to 4 mm.

Has anyone found similar and if so where do I get this tool? The hole in the door is too small for an electric screwdriver bit.

Yes it's a torx driver that you need

Edit: Torx T20 is the size.

You should be able to get one from any Halfrauds type shop or DIY shop

Many thanks Rob. I'll go shopping!

Though I might wait for the weather to warm up before go to work on it.

The guide for removing the door handle on here will help you.

http://briskoda.net/technical-guides/removing-door-handle-fabia-octavia/126938/

I presume that if my handle has been de-locked, the process is still the same?

(I bought the car de-locked so no idea how it's done!)