30M for a shed? That must be one hell of a shed.
Call me old-fashioned, but...
Most of the "ordinary" hangarage in the RAF (as opposed to HASes etc) is of the 1930s C-Type design, which clearly has been fit for purpose for the last 70-80 years.
What is wrong with just pulling out the old drawings and knocking out another copy? It wouldn't even need the blast doors in this case. All it needs is two brick walls, the office/stores building on one side, a steel girder roof and steel panel doors and roof panelling. There are dozens of reference articles, even on the same station!
With a few thousand invested in an architect, the plans could be updated to reflect metric sized everything, modernity in terms of materials, window & door fixtures etc.
I see no reason why this would cost 30 million pounds. Less than 10, I should think.
If the MOD is content to spend money like this, then I can see why there are problems.