The expansion plans have been approved by Luton Council but other councils have complained to the Secretary of State for Communities and Local Government that as the airport is ultimately owned by Luton council they have given themselves planning permission.
After the complaints the Secretary of State got involved and is now looking at whether the council has acted correctly. If he upholds the complaints then the planning application that the council approved would go to a public inquiry which could hold things up for years.
It is interesting that Aena implied that this is all that is holding up the start date and not also the fact that they are still waiting to be privatized.