Are you thinking of XV257? ........on patrol off Land's End on the 3rd June 1984 when a fire in the bomb bay forced the crew to return to their base for an emergency landing. The fire may have been caused by a flare. The Nimrod was not repaired and was used as a spares source before being scrapped.
The Aircraft was not "on patrol", the flare dropped off the carrier and ignited either during or very shortly after takeoff.
The source of the fire was the flare.
The aircraft was repaired.
Apart from that all the details are correct.
YS