Just hypothesising....If you remember that the company was the UK (profits taxable) part of the Walker Trust which is an off shore entity, and that many of the aircraft were leased via off short paper Walker trust companies, you'd probably not be at all surprised why the lease costs were what they were.... When the trust sold the company off, it didn't stop leasing the aircraft. It might have allowed the company to swim on it's own, but the millstone round the neck took a couple of years to begin to lessen, two Q400 per month. Again, just my guess.