As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LHR - FLT 136 - DURING CRUISE, EMERGENCY EXIT LIGHTS ILLUMINATED FOR SEVERAL MINUTES AND EXTINGUISHED. MAINTENANCE CHECKED AND TESTED EMERGENCY EXIT LIGHT SYSTEM UNABLE TO DUPLICATE INTERMITTENT FAULT. SYSTEM GROUND CHECKED NORMAL OPERATION. (M)