Onion, your passion for DTV shines through but there is a need for some reality here.
"In terms of a business case the future plans for the airport include a parallel taxiway. This linked to the fact that airlines would prefer a parallel taxiway means that there is business case for it."
Just because someone would like something does not make a business case. The airlines would prefer lower airport fees; does this justify the business case for reducing the current fees?
The airport is a business and the Board has responsibility to it's shareholders.
Investing in the speculative wish list developments you mention in the hope that they might attract additional airlines and, therefore hopefully, additional passengers, the Board would be seen as negligent in exercising their responsibilities.