Jim, I'm posting these lyrics in response to your request. Do you think this is the same song you heard?
I had hoped I might get out of doing the typing, if I could find a link elsewhere on the web. Well, I did a quick Altavista search and all I came up with was a song or tune by this title is on Bill Whelan's soundtrack for "Some Mother's Son". I saw that film about prisoners on hunger strike, but I have no memory of the soundtrack. Whelan is better known in connection with Riverdance. Perhaps PJ Curtis would have information.

A Ógánaigh Óig - Song of south Ulster origin, author unknown but some say it was Cathal Bhuí Mhic Giolla Gunna (16??-1756), composer of An Bonnan Buíí. I'd like to think a woman wrote the lyrics.The words are published in Amhráin Chúige Uladh, compiled by Colm Ó Baoill. Pádraigín Ní Uallacháin composed her own air for the song and recorded it on "An Dara Craiceann"

A Ógánaigh Óig

A ógánaigh óig dá siúlfá an ród liom
Ba deas do lóistín is do leaba luí
Bheadh fliúit is orgán ag seinm ceoil duit
A thógfadh an brón seo go léir ód' chroí.
Ins na bóithre udaí bhéinn leat i gcónaí
Dá dtabharfá móid dom nach mbeifeá claon
Is dá bhfaighinnse bás is mé sínte i gcomhnair
Le fáil do phóige sea bheinn slán arís.

Is cailín óg mé amuigh ar a' bhfásach
Ag gol go cráite 's ag sileadh deor
Tá leanbh óg ar bhac mo láimhe
'S gan aon deoirín bán agam a bhéarfainn dó.
Dá mbeadh fhios agam féin nach raibh tú i ndán dom
Ní dhéanfainn dáimh nó comhrá leat
Is gur daigne a bhí mise i do ghrása
Ná mar bhíonn na tairní i gcruth na n-each.

Nár dhúirt tú liomsa, a Ghiolla na Ruaidhe,
Nach bhfaighfeá suaimhneas mura b'fhada an íche
Go dtiocfá chugam le do chomhluadar
I ndiaidh do mháithrín a luascadh a luí?
Nár dhúirt tú liomsa go raibh do pháirt liom
Gur i mbun do láir a bhí do ghean 'na luí
'S go déarfá aris nuair a bhí sé 'na lá againn
'Sé mo chrá nár tharla sé ina oíche aris.

'S dá mbéinnse eolach ar dhéanamh ceol binn
Ó thriallfainn leatsa amach san oích'
Go gleannta coille amuigh ar an uaignis
Agus cairde dílse bheith linn a choích'.
Ó bheifeása ' léamh is bheinnse ag foghlaim
A chroí bhig ó is a bhuachaill chóir
Ach ó thréig tú féin mé tá mé úite
Agus beidh mé feasta fad a bheas mé beo.

Translation from IrishGaelic by Pádraigín Ní Uallacháin:

Young man, if you'd walk the road with me
You'd have fine lodgings and a bed to lie [in]
There'd be flute and organ making music
That would lift this sadness from your heart;
In yonder roads I'd be with you only
If you'd promise me that you'd never stray.
If I were to die and [be] stretched in a coffin
My life would return with one kiss from you.

I am a young girl out in the darkness
Crying lamentably and weeping sore
I have a young child in my arms
With no drop of milk to soothe him so.
If I'd have known you weren't for me
I would not converse or lie with you
But my love for you was even stronger
Than the sturdy nails of a horse's shoe.

Did you say to me, young man,
That you'd find no rest if the night were short,
That you'd come to me with your company
After you'd rocked your mother asleep?
Did you not say but that you loved me
That in your very heart your love did lie
And you'd say again when it was morning,
"It is my torment that it's not night again."?

If I but knew how to make sweet music
I would follow you into the night
To the wooden glens away together
And loyal friends with us always.
You would be reading, love, and I learning,
My own and my beloved one.
But since you have left me I am broken
And will always while there's life still here.