Barristers are masters of disguise. The wigs and gowns are mere theatre. Most advocates don't need them as they go about the business of inquisition, indignation, apology, persuasiveness and faked surprise. Robert Jay, QC, the Leveson Inquiry's leading counsel, is perhaps the most televised barrister in UK legal history. Rumpole, remember, was fictional.

Mr Jay's wig was left behind in his chambers and for the past six months he has been hiding behind a cardboard box and odd-looking spectacles. Nonetheless, his disguise is clear enough.

Mr Jay's job at the inquiry is not Socratic magic or the seduction of a jury. His role, like an updated Cicero, is to squeeze out of the inquiry's witnesses anything that might look or sound like the truth, and then leave it to Lord Leveson to do his report's reasoning.

Shock tactics are not required and Mr Jay hasn't used them. His disguise is to pretend to be slow. For a leading silk, shortlisted for "barrister of the year" last year and whose client list includes the Home Office, Defra, and the Secretary of State for Justice, armed with a First from New College Oxford, slow he isn't.

His disguise works best when the person on the receiving end gets too comfortable. The egos on parade at the inquiry have mostly obliged Mr Jay. There's usually nothing fancy at the start; a bit of intellectual wordplay in the middle; and the advocate's finale aimed at unravelling the preposterous. One shaken witness left the stand and asked: "What the hell just happened there?"

Occasionally Mr Jay's disguise as Captain Slow drops; he can't stop himself – in the same way criminal silks raise their eyebrows to the ceiling in view of the jury when a witness is evidently telling porkies.

Having been unable to prevent Rupert Murdoch from presenting himself to the inquiry as an aged sage with a fading memory, Mr Jay on Monday raised his eyes to the ceiling and reminded his lordship that he had a choice. If Mr Murdoch really did have no recollection, then mining further whatever he said would be pointless. But if the Dirty Digger was engaging in "selective amnesia" then, he said, Leveson had to ask what Mr Murdoch's motives and intentions were. News International reply yesterday sounded like this: why hadn't Mr Jay felled the old boy when he had the chance? The same question has been asked of Mr Jay when he did not pull on his hobnail boots, march forward, and give some witnesses a good kicking.

The answer to those who believe Robert Jay is ineffective lies in the confusion that the Leveson Inquiry is a criminal court. It isn't. The criminal bit may come soon enough. But for now Leveson is an inquiry trying not to step on the dangerous territory of the criminal courts. In this demilitarised judicial zone, Mr Jay has to avoid, as they sometimes say in the US courts, being seen to kick ass. But when the Leveson Report is finally published, and the political Kremlinologists go in search of the killer lines, I predict that the leading gold miner will be Robert Jay.