When it came to his big moment to put his case before the Supreme Court the Lord Advocate drew somewhat of a short straw.

A quarter past three in the afternoon is a difficult time to try to set out any kind of argument, let alone a complicate legal one.

Winter being what it is, the light gradually ebbed as he talked. Or perhaps that was just how it seemed in the gloomy, cramped courtroom.

Scotland's most senior law officer is also the possessor of a very calm, sonorous voice,

He speaks in the kind of tones harassed parents would pay good money for to sooth howling children to sleep.

But if anyone involved in the proceedings was feeling the need for a post-lunch nap they showed little sign of it.

At one point one of the Supreme Court justices asked the Lord Advocate for a reference.

"It is quoted in my written case at MS 1612," came the reply.

"Paragraph?", the judge shot back, quick as a flash.

"Paragraph 76, subparagraph 4, right at the top of the page," the Lord Advocate replied with, it has to be said, something of a flourish.

Adding, for those perhaps falling behind at the back, "It is paragraph 9 of the explanatory notes".

Pages rustled behind him.

Proving that, once again, no law is too old for this court case, his argument rested, in part, on the 1707 Act of Union.

That established that changes to legislation affecting Scotland could be agreed by the Westminster parliament not by the Crown, he said, for which read the UK Government.

But there were more modern references as well, including to the 2016 Scotland Act, which said that Westminster would ask Holyrood before legislating in devolved areas.

But what, suggested another of the justices, if they just did not bother?

Mr Wolffe said that he was taking Parliament at its word. His inquisitor looked doubtful.

Just moments later the justices appeared to accept that the time was against them.

Instead of carrying on until 4.30, they broke up at 4pm.

The Lord Advocate will continue his argument later today.