Sorry - been back to UK for the weekend.
No, I'm not unrealistic, just someone with literally a lifetimes experience of the Services.
If anyone takes drugs in the military and get caught by the random testing, and no-one is exempt, no matter how senior; they will get booted out. My dh was tested, and had to be retested as they didn't like the colour of the urine test; he just drank loads of water as he worked in a v hot office.
The Forces do as much as possible to prevent drug usage, and most are sensible. Would you want someone stoned watching your back in Afghanistan or flying million of pounds worth of fast jet? They all know it is prohibited and what the consequences are.
Last time I looked, British Aerospace were civvies, not military, and so are under different rules.
Can we also get away from it just being the Army there please? There are roughly 450 RN personnel there at any one time, not counting the Royal Marine contingent (they are Navy incidentally, NOT Army), and the RAF have several out there as well. It is a tri-service op. There is some privatisation, but that tends to be in terms of the supply chain more than anything else; and as lots are ex military, they know what they may be getting into.