As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: AN EMERGENCY WAS DECLARED ON ENTERING LHR AIRSPACE DUE TO AFTER MIA DEPARTURE, ON GEAR RETRACTION, TIRE PRESSURE MESSAGE / AMBER MLG, NO. 8 TIRE. AIRCRAFT LANDED SAFELY AT LHR WITHOUT FURTHER INDECENT. MAINTENANCE FOUND NUMBER 8 TIRE HAD LOST ALL PRESSURE. REPLACED NUMBER 8 WHEEL ASSEMBLY PER AMM 32-45-01-000-801 AND AMM 32-45-01-400-801.