CessnaEng,
In your post you said
"Trade creditors / debtors are a normal part of business so I don't think you can claim the moral high ground by saying the airport shouldn't have let the debt mount up."
Did you know the credit given by the airport to Comed, that you say is a normal part of business, had accrued over a period of 18 Months and reached almost £700,000, that can not be "normal"!
My suppliers say payment by the 28th of the month after the month of invoice or NO more supplies on the 29th. That is normal in the real world, unless there is an hidden agenda!