It's on top of the inlet manifold I'll try and find a guide or piccie for you. It's a little grey device with 2 screws holding it in place and a multiplug attached.
By the way if your local to David Hendry and interested in meets, shows etc then give Scooby Princess a shout and she'll give you some details (she is the South West regional organiser also check out the South West Scoobies section