the Govt don't have specialist contract negotiators/writers (I believe we used to once upon a time)
In MoD this may have gone full circle. Commercial staff are encouraged to gain professional qualifications, although how they compare to industry professionals I don't know.
Setting this aside, there are two sure-fire ways to a successfully and timely contract being awarded. One, get the company to draft it. Most delays are caused by Commercial faffing around for months over terms and conditions, trying to get the company to accept unsuitable ones. It ain't a contract until MoD agrees it is, so there can never be any harm caused. Two, the technical project manager negotiates and agrees the contract, as used to be the case with anything airworthiness or repair related. Commercial don't like this as they are taught, wrongly, only they can sign a contract. Read the regs and get over it. Underpinning this, make sure the Schedule of Requirements reflects what the Service really needs and what is possible; which seldom aligns with what DEC asks for. Downside - to achieve this you need experienced, trained technical staff. Otherwise, it's straight forward.
But none of this counts for anything if you get a political over-rule, to let the contract on a company who didn't bid, who happen to be in a Defence Minister's constituency. Perhaps not a million miles from the Carillion problem.