The discussion is not about Procurement. It is about the first step - establishing and articulating the Requirement. History tells us that if this is done correctly and accurately, and there is no subsequent political or Service interference, most projects are delivered with effortless competence.
Given that, the answer is yes. The Defence Committee, or a body with the necessary authority, could act as a guard at the procurer's door, with a huge sign saying "**** off".
Regarding the new carriers, I found myself at a briefing in 2002. A young man stood up and informed us that the catapult question was cost-neutral, so there would be none initially and they could be added at any time if needed. Another slightly older gent told us that MASC (formerly FOAEW) was entirely unrelated to Sea King AEW Mk2 or ASaC Mk7, and he was starting all over again. Now, that's where we have big problems!