You do not have to guess how much running the airport costs. The accounts for 2005 are on the companies house website for anyone with £1 to see. (the 2006 accounts are still overdue according to website).
in 2005 they had 155 operational staff and 21 management/admin.
The wages were £3,890,210 and staff bill was £4,431,909 after pensions and Social Security was added. Additionaly directors were paid £322,599.
the loss for 2005 was £1,062,887.
web site
http://www.companieshouse.gov.uk/