What I was getting at is do we all drive cars with the best NCAP ratings available, or do we have to compromise because of the potentially high cost of getting the Utopian solution.
You are absolutely right that compromise is a necessary part of any procurement. From a Health & Safety perspective though, the term "reasonably practicable" means balancing risk against cost. The greater the risk, the more reasonable it becomes to go to substantial expense, trouble and invention to reduce it.
If the Metropolitan Police can be challenged in court by the HSE, shouldn't the MOD be concerned?