Watching Lord Pannick QC addressing 11 justices of the Supreme Court is like watching one of the great maestros conducting a symphony orchestra. Sitting at the back, you have a rear view of a standing figure looking at pages of notes. All the work is apparently being done by the people facing you. On television, though, you can see who’s really calling the tune. It’s only when others give it a try that you realise how much effort goes into making it look effortless.

In September, Pannick persuaded the UK’s highest court that Boris Johnson’s suspension of parliament for five weeks in the run-up to a crucial Brexit deadline was unlawful. The consequences were dramatic: MPs and peers returned to Westminster a day later and carried on where they had left off. Though parliament was lawfully prorogued in October ahead of the planned new session, Johnson was required to spend two hours in the Commons answering questions on his Brexit proposals.

‘When Pannick speaks,’ one senior figure told me recently, ‘judges listen.’  The fees can be legendary but he may also act pro bono if he is interested in a claim

Reflecting on the ruling, Pannick said it had transformed “what many had dismissed as a hopeless legal argument to what is now widely regarded as a plain and obvious conclusion”. I was one of those who thought his arguments would be thrown out — not because I thought Johnson had complied with the unwritten conventions of the constitution, but because I regarded the issues as political rather than legal. My view was shared by the three most senior judges in England and Wales. Not for the first time, the Supreme Court was swayed by Pannick’s advocacy.

How does he manage it? The first requirement is a detailed knowledge of all the leading cases. Any judge with the temerity to suggest that an earlier decision does not support the proposition Pannick is relying on will be steered politely but firmly in the right direction. But his main technique is to argue clearly and compellingly. He starts with what appears to be a truism. His second point follows entirely logically. And that, in turn, leads inexorably to a conclusion that the court is forced to adopt.

“When Pannick speaks,” one senior figure told me recently, “judges listen.” That’s why he is also briefed, outside his main area of expertise, to represent wealthy Middle Eastern clients in family law cases. The fees are legendary. But if he is interested in a claim he may act pro bono, appearing without charge.That’s how he came to represent Gina Miller once again.

In June, there were rumours that the new prime minister might try to ensure that parliament was not sitting at the end of October, thus thwarting MPs who wanted to block a no-deal Brexit. In his fortnightly Times column, Pannick argued that this would be a breach by Johnson of parliamentary sovereignty, a fundamental constitutional principle. “If he were to advise the Queen to prorogue parliament in these circumstances,” Pannick predicted, “the courts would be likely to hear an urgent application and then declare his advice to be unlawful.”

Johnson’s prorogation plan, when it emerged at the end of August, was slightly different: although parliament was to be suspended for more than a month, it would still have sat in the two-and-a-half weeks running up to 31 October. But Miller’s solicitors, Mishcon de Reya, were ready to challenge any attempt to suspend parliament for what were seen as political reasons. They issued proceedings against the prime minister a day later while Pannick arranged to return early from a family safari in Botswana.

After three days of argument, the Supreme Court found in Pannick’s favour. Just as he had predicted, all 11 justices agreed that “an unlimited power of prorogation would . . . be incompatible with the legal principle of parliamentary sovereignty”.

Still smarting from being traduced as “enemies of the people” after Pannick had first persuaded the High Court that Miller was right about the primacy of parliament, the judges must have known that another judgment in her favour would lead to calls for political vetting of judicial appointments. Fortunately, the attorney general, Geoffrey Cox, confirmed the government had “no current plans” to introduce US-style confirmation hearings.

Supreme Court justices, like other senior judges, are addressed in court as “My Lord” or “My Lady”. Though the justices know him well, they must call him “Lord Pannick”. If he or another counsel wants to refer to something said by one of the justices, Pannick will use the formula “my lady, Lady Hale”. Other counsel are meant to refer him as “my friend, Lord Pannick”. In the heat of the moment, his opponents occasionally call him as “my lord, Lord Pannick”. It’s a reminder of what might have been if Pannick had decided to join the judiciary — but who needs to be a judge when your arguments can be the first draft of precedent?