Well, it depends on the amortization convention of course. Certainly it's straight line over the life of the underlying contract - and if that contract is extended, it could be extended even further I believe, but it depends on how it starts - 1/2 year, monthly, etc.
Regardless, it appears we have paid most of our fees for the past year up front to the tune of $100M. My guess is that "trade debtors" is not as much about deferred transfer payments, but the accounting terminology is different in the UK than it is in the states. I also haven't done much commercial accounting recently, so I'm a bit out of practice.
So in summary, it appears that we've mostly paid our fees up front and have minimal liabilities on our transfer dealings. Thus, we likely don't owe much to Swans or anyone else, so we shouldn't have cash flow issues in the future. That's a very good thing. I personally haven't crunched through the statements to determine how much cash we'd have for transfer dealings this year, but obviously, we all know that our salary bill is super high and needs to come down.