The song was published originally in a little booklet called "Sangs o' the Stane", n.d. but must be 1951, ascribed to Johnny McEvoy, a Glasgow singer. I have heard since that it's actually by Josh MacRae, who does exist, also from Glasgow. Words & music are in Norman Buchan's anthology "101 Scottish Songs". Here it is as I remember it:

Oh the Dean o Westminster was a powerful man
He held a' the strings o the state in his han',
But for a' his great business it flustered him nane
Till some rogues ran awa wi his wee magic stane.
[Singing toorali-oorali-oorali-ay.]

Noo the stane had great poo'rs that could dae sic a thing,
But it seems that withoot it, we'd be wantin a king;
So he called in the polis and gave his decree,
"Go and hunt out the stane and return it to me."

Sae the polis went beetlin way up to the north,
They huntit the Clyde an they huntit the Forth;
But the wild folk up yonder were nae use ava,
For they didnae believe it was magic at a'.

The Provost o Glasgow, Sir Victor by name,
Was awfu pit oot when he heard o the stane,
An he offered the statues that stand in George Square,
That the High Church's masons might carve a few mair.

When the Dean o Westminster wi this was acquaint,
He sent for Sir Victor an made him a saint;
"Now it's no use your sending your statues down here,"
Said the Dean, "but you've given me a jolly good idea."

Sae he quarried a stane o the very same stuff,
And dressed it a' up till it looked right enough,
Then he sent for the press and announced that the stane
Had been found and returned to Westminster again.

When the reivers fand oot what Westminster had done,
They went aboot diggin up stanes by the ton,
And for each wan they finished, they entered a claim
That this was the true and original stane.

But the cream o the joke still remains to be telt,
For the bloke that was turnin them aff on the belt,
At the peak o production was sae sairly pressed,
That the real yin got bunged in alang wi the rest.

Sae if ever ye come on a stane wi a ring,
Jist sit yersel doon and appoint yersel king;
For there's nane could come forret to challenge yer claim
That ye crooned yersel king on the Destiny Stane.

[This goes to the first half of the "Ould Orange Flute", or to the practically identical "Villikins".]

There are other songs in the original booklet, but none has lasted (or deserves to last, let's face it), but this one, which I count a real classic.