Update on the central loocking 'anti-hijack'.
I tried the method of setting the ignition to 'A' then holding in the dach 'lock' button but nothing happend.
I then stated the engine, then held the lock side of the button down, after about 5 secs a beep was heard. After driving off about 10 secs later the doors auto-locked!
Success at last!
Cheers for all those who helped!