Just to set the record straight, the aircraft in question did not have an engine failure on take off or at any other time. The aircraft generated ENG 4 REVERSER and ENG 4 REV LIMTD status msgs and the associated EICAS advisory messages. After consultation with maintrol it was decided that a precautionary shut down and return to LHR would be the carried out.
The cause of the messages was damaged wiring to the thrust rev motor, caused by a failed airmotor shutoff valve. The integrity of the T/R was not compromised and it was still locked in the fwd thrust position on arrival. So NO it had NOT deployed in flight!