A STRANGE political alchemy is often at work in the crucible of First Minister's Questions.

Facts, given a second glance, vanish like mist.

Or else Labour, if the lighting's just right, can seem like a vaguely credible opposition.

And so yesterday, right before our very eyes, promises which had appeared to be solid gold were transmuted into the base metal of wishful party policies.

It started with Labour's Johann Lamont reminding the FM of his "cast-iron position" that a post-Yes Scotland would use the pound.

Now his own civil servant had said a currency union wasn't a definite fact, just the desired option. So where was the Plan B?

Alex Salmond, who owns more rose-tinted specs than Elton John, was insouciance squared.

This month's White Paper was going to be "definitive", he purred, although only on "SNP policy choices".

Translation: fans of the facts may be disappointed.

"Well that wasn't so much cast-iron as brass neck," said Ms Lamont.

Brass neck?! a galvanised First Minister glared.

Brass neck was Labour asking others to vote down the bedroom tax in the Commons on Tuesday "then 47 Labour MSPs, including 10 for Scotland forget to turn up.

"When it comes to brass neck the SNP will have to go a long way to beat the Labour Party's brass neck on the bedroom tax".

It was a copper-bottomed, tin-hatted ding-dong.

Not to mention a steel-plated diversionary tactic.

"It would seem we have a fool here who has no Plan B," retorted Ms Lamont, staying classy.

The scrapping continued when Tory Ruth Davidson raised a Dundee prof who backed the Union, only for an SNP minister to nag his principal.

Suppression of academic freedom, she said.

That was nonsense, Mr Salmond announced.

It was all too much for Siobhan McMahon, an alumnus of Lanarkshire Labour's Charm School, who then began sputtering like a smelter on the backbenches.

The Presiding Officer suggested she "desist".

The volcanic Ms McMahon cooled to a low grumble.

A later Tory complaint got short shrift too.

It was that other non-stick, Salmond alchemy at work: no matter what the headache is, it always seems to his challengers who are foiled again.