The late noble Lord Diplock:
"The jury … should remind themselves that the postulated balancing of risk against risk, harm against harm, by the reasonable man is not undertaken in the calm, analytical atmosphere of the court-room after counsel with the benefit of hindsight have expounded at length the reasons for and against the kind and degree of force that was used by the accused: but in the brief second or two which the accused had to decide whether to shoot or not and under all the stresses to which he was exposed."