Found it! The song is called "The Hielan' Man"
by Matt McGinn. It may not be what you are after but I
hope you enjoy it anyway.

THE HIELAN' MAN
(Matt McGinn)

Ten thousand Roman sodgers
To the Hielans they came north.
And they had conquered millions
Frae the Tiber tae the Forth.
They landed near Loch Lomond
For the night they thought they'd lie
But frae somewhere on the Cobbler hill,
They heard this terrible cry

Chorus:
Gregali, Gregaloo!
Come up and fight ya cowardly crew,
I'll have you for my pot of stew;
You're feart tae fight wi' me!

On top was a a bearded hielan man
Wi' a kilt and a big claymore;
He looked a bit ferocious
So old Caesar sent up four.
Then he sat doon tae supper
By the bright light o' the moon,
But he lost his taste for vino
When four heids came rollin' doon.

Chorus

Then he sent up Mark Anthony
Wi' another fifty-five:
'Go bring tae me that rascal's heid,
Or I'll have ye skinned alive!'
Thet heard a clash o' metal then
Until the night was done;
But then there came this terrible cry
Wi' the risin' o' the sun.

Chorus

He next sent up a thousand men
This hielan man tae crack;
But oot o' a' that thousand
There was only one came back.
'O Caesar,' screamed the sodger
Wi' his heid a' black and blue,
'That rascal has been kiddin' us,
There's not just one - but two!'

Chorus

So Caesar picked his suitcase up
And he ran southwards then.
He was doin' eighty miles an hour
But he couldnae catch his men.
Now maybe you will wonder
Why I've told this tale at all;
Well, it has a simple moral
And they call it -
HADRIANS WALL