Two places, the BBC article from the OP (Scorpion + F-35 per hour figures), and this Times article from 2013: http://nation.time.com/2013/04/02/costly-flight-hours/

Since I posted the above I have learnt that the Global Hawk Drone's per hour cost has decreased quite substantially. It is now closer to 18.9K/hour, instead of 49K per above.

You can read more about that on this Wikipedia article:

https://en.wikipedia.org/wiki/RQ-4_Global_Hawk#Cost_increase...