Flight Heathrow Airport departs from London Heathrow Airport at 20:55 and arrives at Mumbai Chhatrapati Shivaji International Airport at 11:15.
The flighttime is about 9h 50m. The distance travelled ("as the bird flies"): 8456 Km. So the average speed is roughly 860 Km.
There is an 4.5 hour time difference between London and Mumbai