[Cecilie]

Norwegian at the launch of winter 2015 season will begin to adopt flight number “D8″, initially on flights from London Gatwick for European routes. Certain service from London Gatwick will be using “D8″ flight numbers from 25OCT15. From 27MAR16, Norwegian service for the remainder of London Gatwick, flights to/from Spain, as well as Helsinki, will also see flight number switches from DY to D8.

http://airlineroute.net/2015/07/09/d8-w15/