Given that it was no more than a decision of the Divisional Court, and a pre-War decision at that, the case of Duncan v. Jones [1936] 1 K.B. 218 has exercised a remarkably enduring influence. The case appeared to give the police enormous operational discretion in dealing with actual and prospective breaches of the peace. When a constable reasonably apprehended a breach of the peace, he could take steps (arguably, only reasonable steps) to prevent it or its recurrence. This disarmingly simple formula made it very difficult to challenge, let alone control, the way in which the police exercised their powers.