No Government has had an Aviation policy for many years. Not since they sold off BAA et al.
Alistair Darling tried, but ripped up what he had written as soon as he got to the Treasury. (Who remembers runway 2 at Stansted, a poss runway 2 at lgw,and runway 3 at lhr??)
The main reason is that the DfT is seen by ambitious Civil servants as a career graveyard. The CS know that a move to the DfT is the end of their careers. The only place with a worse collection of CS is the Min of Ag., or whatever they call it now.
If a fast track civil servant gets anywhere near the DfT, they quickly come off the track - or leave, sharpish.
Ditto with Ministers. they are only at the DfT to either launch themselves in to a better job, or into political oblivion.
Until this changes, forget any notion of a National Aviation strategy.