I would advise anyone to read and take note of what Colin (Spanner Juggler) has to say. My list is less technical, but this is what I carry:
Jack + long jack handle (I cannot raise the car with the short jack handle supplied)
Long wheel nut spanner (for centre hexagonal wheel nut)
Axle stand(s)
Wheel chocks
Tyre inflator
WD40
Toolkit
Fuses
Hose/radiator tape
Gaffer tape
Water
Oil
Tyre foam
Spare bulb kit
Knee pads
Collapsible bucket
Cable locks (for any luggage left unattended in the car while you wait in a cafe/pub for the breakdown service to arrive!))
Rainex
Autoglym bird wipes
French trips
Injection relay
Accelerator/Clutch cables
Starting/clearance instructions in French
Reflective triangle
Reflective jackets
Breathalysers
Headlamp adaptors
Breakdown docs
Original V5
Original insurance docs
