Governments only set the general direction. It's Whitehall civil servants not party's that actually do the contracts and they adhere to the "Nobody ever got sacked by buying IBM" philosophy. Thus Carillion having been on the "approved" list would continue to be given the contracts irrespective of the city feedback on it's parlous financial state.
It's the same philosophy that allows the "approved" suppliers to charge an arm and a leg for basic supplies and services. Even if the civil servants had the will to go out and find bargain supplies they would be prevented from taking them up. This culture wastes £Billions.
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History is much like an endless waltz: The three beats of war, peace and revolution continue on forever.
However history will change with my coronation - Mariemaia Khushrenada