hmmm, the clutch shouldnt initiate any lights, so it sounds like you have a short on the brake wire.
Have you checked the sensors around the rear of the pedals?
if there's a ground fault/short,pressing the clutch will cause this, as clutch position sensor works off part of the same system i believe. this might be one for a good auto-sparky.
If the cause doesnt become obvious after having a look round the pedal area/pedal sensors/wiring,it might be worth taking it to your local ford dealer as their IDS/VMM should crack the problem.
dont suppose its possible for his brake pedal sensor to be fitted to his clutch pedal by mistake.??dont even know if its physically possible . do you have cruise control?