Claim for damages for negligence/employer’s liability – Attack on armed police officer at a police station by member of the public who was a visitor to the police station compound – Duty of care owed by occupier of police station compound to person working within that compound – Duty of care owed by government to persons working on and visiting that compound – Res Ipsa Loquitur – failure of defendant to do anything other than put claimant to proof of his case – Failure of defendant to lead any evidence or to challenge the claimant’s case in any significant way during cross – Examination of the claimant – Prima facie case not equivalent to proof of case on a balance of probabilities – Whether defendant in breach of duty of care owed to claimant