In case you missed it:
12.1 In considering the duty of counsel retained to defend a person charged with an offence who confesses to his counsel that he did commit the offence charged, it is essential to bear the following points clearly in mind:
(a) that every punishable crime is a breach of common or statute law committed by a person of sound mind and understanding;
(b) that the issue in a criminal trial is always whether the defendant is guilty of the offence charged, never whether he is innocent;
(c) that the burden of proof rests on the prosecution.
12.2 It follows that the mere fact that a person charged with a crime has confessed to his counsel that he did commit the offence charged is no bar to that barrister appearing or continuing to appear in his defence, nor indeed does such a confession release the barrister from his imperative duty to do all that he honourably can for his client.
12.3 Such a confession, however, imposes very strict limitations on the conduct of the defence. a barrister must not assert as true that which he knows to be false. He must not connive at, much less attempt to substantiate, a fraud.
12.4 While, therefore, it would be right to take any objections to the competency of the Court, to the form of the indictment, to the admissibility of any evidence or to the evidence admitted, it would be wrong to suggest that some other person had committed the offence charged, or to call any evidence which the barrister must know to be false having regard to the confession, such, for instance, as evidence in support of an alibi. In other words, a barrister must not (whether by calling the defendant or otherwise) set up an affirmative case inconsistent with the confession made to him.