At the end of the day,it's the Treasury's ball, and they can take it home on a fit of pique if they wish.
Nice try pulling out of a variety of treaty commitments - which become part of our municipal law - and hope we never have any need for LRMPA, strategic intelligence, ABO, UK NEOs, SLOC protection, overseas training areas, defence industry cooperation.......
We are not Switzerland or Sweden. The UK remains a global player in many, many fields and Defence plc is a significant part of that, howsoever 'poorly' resourced.