Took it to Peugeot Dealer who said ''Plip'' had gone (?) and a new one would be £160. Any ideas where l can get one cheaper ?

unfortunately no, as far as l was told ya can only get them from your car maker alone

You can find them for sale on ebay, obviously the blade on these keys will be different but may be able to swap them and the immobiliser chip.

Here are instructions on how to program rcl plip:

http://peugeotdiesel.com/Program_Peugeot_406_Key.html

Details of the key and transponder :

http://peugeotdiesel.com/Peugeot_Keys_Info.html