LHR load factors
Bagso
I think you are being a bit too selective in quoting low loads at Heathrow. In fact the average load factor at Heathrow in 2013 was 76.4%, according to the airport's owners. As a year-round figure it's difficult to see this increasing much for reasons that Skipness and other airline types will be familiar with. Seasonality will always reduce annual LFs, with peak summer load factors in the mid-80s.
In relation to slot values, few airlines include these on their balance sheets - BA don't, for example. The airlines that do tend to be the more desperate ones, eager to shore up an otherwise dodgy balance sheet. FlyBe include them on the balance sheet, and I think that bmi used to do so - need I say more?