Military partners at Leeming is exactly correct. They are still civilians who are partners to the military.Even though they have access to most operational systems there is still the security headache of accessing a military base. On top of that they are not exclusively contracted to the MOD. They could secure contracts with others ,highy unlikely I realise ,for downtime with their aircraft. On top of that they operate " pretending to be exercises " at regular intervals and operating into a civilian airport makes them more realistic.