I see that the Telegraph article says that the 747's carry between 500 and 600 passengers? Are they talking about Japanese domestic 747's?!?!?
They also state that BMI operates as a BA Franchise, think they meant BMED! Nice journalism again I see.
The flights are empty one way but what it fails to mention is they pick up passengers at the other end. Not only does it protect the slot but it means that 300 pax on the aircrafts return leg are not disrupted.