So, does it save money on the project if we keep on crashing them?
I very much doubt that. The contract will probably have either a "take or pay" structure that means the payments to Thales and their fellow bunglers are guaranteed regardless of losses (because lord forbid they should lose out if a few were shot down). Or they'll have a "loss of profit" clause if the volume of work declines from that expected, in which case we save a tiny bit, but they make as much money overall.
MoD Procurement is a name associated with deep and abiding incompetence, and with a long and distinguished history of failure. Their amateurish buyers will be no match for the well structured, professional, experienced and heavily incentivised teams of lawyers and technical sales people doing the selling.
The way to "sew up the pocket" would be to cast MoD Abbey Wood into some other dimension of time and space.