It was composed by Robert Gilfillan of Dunfermline (1798-1850), and published the year after his death; the tune was also his suggestion.

See:

'Poems and Songs' (R. Gilfillan, 1851) pp. 164-166
'Vagabond Songs & Ballads' vol. 2 (R. Ford, 1901) pp. 53-55 'Whistlebinkie' vol. 1 (pub. D. Roberston, 1905 edn) pp. 423-424

Here's Robert Ford's write up:

"I'VE AYE BEEN FOU' SIN' THE YEAR CAM' IN

Air—" The, Laird n' Cockpen."

        I've aye been fou' sin' the year cam' in,
        I've aye been fou' sin' the year cam' in ;
        It's what wi' the brandy, an' what wi' the gin,
        I've aye been fou' sin' the year cam' in !

Our Yule friends they met, and a gay stoup we drank,
The bicker gaed round, an' the pint-stoup did clank;
But that was a nae thing, as shortly ye'll fin'
I've aye been fou' sin' the year cam' in !

Our auld timmer clock, wi' thorl an' string,
Had scarce shown the hour whilk the New Year did bring.
When friends and acquaintance cam' tirl at the pin
An' I've aye been fou' sin' the year cam' in !

My auld Auntie Tibbie cam' ben for her cap,
Wi' scone in her hand, an' cheese in her lap.
An' drank a gude New Year to kith an' to kin
Sae I've aye been fou' sin' the year cam' in !

My strong brother Sandy cam' in frae the South
There's some ken his mettle, but nane ken his drouth ;
I brocht out the bottle, losh ! how he did grin !
I've aye been fou' sin' the year cam' in !

Wi' feastin' at nicht, an' wi' drinkin' at mom,
Wi' here tak' a caulker, an' there tak' a horn;
I've gotten baith doited, an' donner't an' blin'
For I've aye been fou' sin' the year cam' in !

I sent for the doctor an' bade him sit doun,
He felt at my wrist, an' he straiket my crown
He order'd a bottle—^but it turned out gin
Sae I've aye been fou' sin' the year cam' in !

The Sunday bell rang, an' I thocht it as weel.
To slip into the kirk, to steer clear o' the de'il;
But the chiel' at the plate fand a groat left behin'
Sae I've aye been fou' sin' the year cam' in !

'Tis Candlemas time, an' the wee birds o' Spring
Are chirming an' chirping as if they wad sing:
While here I sit bousing—'tis really a sin !
I've aye been fou' sin' the year cam' in!

In the month of May not many years ago a man was arraigned at the bar of a West of Scotland Police Court for being drunk and incapable, and when asked if he was guilty or not guilty, he modestly admitted the impeachment, but leering in the face of the presiding magistrate, pled in extenuation " thae awfu New Year times." A similar case of long-sustained hefuddlement perhaps, many years before, gave Robert Gilfillan, the author of " Why Left I My Hame," who was himself certainly a most temperate and exemplary man, the hint for this rarely graphic and clever bacchanalian song. It can be sung with rare effect and is not without a moral—to the wise."