The case went to the House of Lords but Lord Denning’s comments in the Court of Appeal concerning the role of counsel remain apposite.
Lord Denning MR said (p501),
[The role of the barrister]
As an advocate [the barrister] is a minister of justice equally with the judge. He has a monopoly of audience in the higher courts. No one save he can address the judge, unless it be a litigant in person. This carries with it a corresponding responsibility. A barrister cannot pick or choose his clients. He is bound to accept a brief for any man who comes before the courts. No matter how great a rascal the man may be. No matter how given to complaining. No matter how undeserving or unpopular his cause. The barrister must defend him to the end. Provided only that he is paid a proper fee, or in the case of a dock brief, a nominal fee. He must accept the brief and do all he honourably can on behalf of his client. I say “all he honourably can” because his duty is not only to his client. He has a duty to the court which is paramount. It is a mistake to suppose that he is the mouthpiece of his client to say what he wants: or his tool to do what he directs. He is none of these things. He owes allegiance to a higher cause. It is the cause of truth and justice. He must not consciously mis-state the facts. He must not knowingly conceal the truth. He must not unjustly make a charge of fraud, that is, without evidence to support it. He must produce all the relevant authorities, even those that are against him. He must see that his client discloses, if ordered, the relevant documents, even those that are fatal to his case. He must disregard the most specific instructions of his client, if they conflict with his duty to the court.
[The Code of Conduct]
“The code which requires a barrister to do all this is not a code of law. It is a code of honour. If he breaks it, he is offending against the rules of the profession and is subject to its discipline […] . Such being his duty to the court, the barrister must be able to do it fearlessly. He has time and time again to choose between his duty to his client and his duty to the court. This is a conflict often difficult to resolve: and he should not be under pressure to decide it wrongly. .. If a barrister is to be able to do his duty fearlessly and independently, he must not be subject to the threat of an action for negligence.”
 This is no longer true.
 See now s.176 (1) of the Legal Services Act 2007.
Edited for ease of reading.
This reading is of historic interest. The BSB Code of Conduct (contained in the BSB Handbook) now governs the ethical behaviour of barristers.