Outside, students were demonstrating in favour of their inalienable right to get completely blootered by buying as much cut-price booze from the nearest off-licence as they could. Inside, the First Minister was demonstrating in favour of his inalienable right to push through unworkable policies, despite the combined opposition of pretty well everybody else.

The students - and pretty well everyone else - are so far having their way. The SNP's proposed ban on selling alcohol to under 21-year-olds seems doomed, if the combined weight of the opposition parties is anything to go by. Come to think of it, the combined weight of the opposition parties is not something to go by, so maybe it stands a chance.

In the meantime, however, Mr Salmond was up against the combined weight of Iain Gray, the Labour leader, who described the plan as “unfair, unworkable, ineffective, and ...” - we half-expected to hear “undrinkable”' but he fell back on “frankly daft”, which doesn't sound so good. He added that the SNP's proposals were opposed “by young people themselves”, as if that was a good enough reason for dropping them, and then went on to say that the “ultra-loyal” student Nationalists were also against them.

This attracted guffaws from listening SNP backbenchers who plainly felt that calling the student Nationalists ultra-loyalist was

a) misplaced and b) frankly daft,

so Mr Gray amended his description to “usually ultra-loyalist”, which somehow spoilt the point of the whole thing.

Now, however, something unusual happened. Mr Gray made a joke. This needs to be recorded, because it is a first - well, he's only been in the job for five minutes so maybe that's not so extraordinary. Anyway, here goes. He said that Mr Salmond had appeared in the “Colemanballs” column of the satirical magazine Private Eye, which mocks inept quotes, usually from sports commentators. Mr Salmond had apparently said: “That's not just a legacy, it's there for the future.”

This is certainly worthy of mockery, but Mr Gray should know that to mock Mr Salmond is to invite retribution - which duly came. For the First Minister had, conveniently to hand, a copy of The Sun newspaper, which had carried an interview with Mr Gray. It reported that Mr Gray was so dull that half-way through, the interviewer had lost the will to live. It appears that, to liven up his image, Mr Gray's political team has suggested calling him something more dynamic, like “Danny Invincible, the Kilmarnock striker”.

The First Minister liked the idea, and contributed his own joke: “From now on I will refer to Iain Gray as Invincible Iain Gray - or perhaps Interesting Iain Gray.”

I mention these exchanges only in the interest of conveying the intellectual heights we reach in our beloved parliament these days.

Annabel Goldie, for the Tories, was also keen on the students - indeed she had joined their demonstration. But she described them as “responsible adults”, which surprised most people - including, I suspect, the students. By the end of these exchanges I began to sympathise with Mr Salmond, which is something that happens rarely. He is, after all, only trying to stop people drinking too much and students, as we all know, drink too much. They are not the only ones, of course, but at least they are a start.

The fact that everyone is against him, from students to ultra-loyalists and responsible adults, sounds like an excellent reason for pressing on. As Marshal Foch so memorably put it: “My centre is giving way, my right is retreating, situation excellent, I am attacking.”

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