Some more background:
A few weeks after the departure in question, media reports began to emerge that complaints had been received, initially by the local authorities who passed the details to NATS. NATS in turn notified the AAIB, who delegated the investigation to the authorities in India.
Heathrow, somewhat disingenuously, removed the flightpath from its public WebTrak system, though it was still possible to see the noise monitors registering the passage of the aircraft above them:
When queried, Heathrow responded that the suppression was in line with the policy that "when a flight is being investigated by Air Traffic Control and the airport for reasons not associated directly with community noise the airport will suspend public visibility of a specific flight" and that "pending investigation the flight track may be reinstated" (though in fact it didn't reappear within WebTrak's 12-month historical window).