Don't think I've come across that one Mick.
I find I have 15 variations on the theme - yours may well be among them, but if not, I'll add what you sent
The version that bears the 'S' number in the BBC(may well stand for 'secret'), is the one recorded from Thomas Moran of Leitrim.
I used this and a 'lament' type version in a talk I once gave on song and history - lovely contrast in approach to the subject.
I'd give my right arm for a decent recording of the other, sung at a live concert my a great singer, Thomas Creamer.
One of the legends connected with the killing was that one of the assassins was 'Rory of the Hill' who was a victim of Clements' 'Droit du seigneur" when his wife was lawfully 'broken in' by 'is Lordship on their wedding night.
Jim Carroll

Lord LEITRIM
Thomas Moran, Mohill, Leitrim

O you boys of the shamrock, give ear to my ditty.
Be alive to your duty, be wise and be witty.
You keep your powder dry and we'll make the tyrants fall,
And we'll give them what Lord Leitrim got up there in Donegal.
To me whack fol the dero, fol the riddle dee.

It being on All Fools' Day the debaucher left his den,
Leaving gamblers, bums and harlots in his castle of Lough Lynn.
To make his men courageous he gave a hellish call,        
Crying:   "We'll tumble all the cabins up in County Donegal 1"

'Twas but a few hours after, old Meehan he did say:
"Oh, my lord, I feel a horror we'll meet Rory on the way.
"His lordship then made answer in the presence of Kincaid, Saying:
"Of Rory or the devil, sure, I never was afraid."

On the second day of April the old viper passed this way
Till he came to Gortha Wood at an angle of the sea.
There stood Rory of the Hill, who never feared a ball,
To protect the decent widows in the County Donegal.

When Rory saw them coming, sure, his heart did jump for glee.
He cried: "Three cheers for Tenants' Rights, Home Rule and liberty!"
And then as he approached them he made a low salute,
Saying: "Where are you going today, you stinking ugly Orange brute?"

Oh, this monster's face began to foam, his venom he did spew,
And he roared out in a hellish tone: " Come tell me, who are you?"
"Well, my lord, I'm Rory, That makes you welcome all
To a bloody dose of bullet pills up here in Donegal. "

"Spare us our lives," says Meehan, "Bold Rory, if you please."
"Oh no, for if you lie with dogs you're sure to rise with fleas."
The gay boys behind the wall, oh, they was laughing at the joke,
Saying: "Today we'll blow this bugger off with powder, ball and smoke."

"Come, all my boys," says Rory, "Make ready, present and fire!"
At his lordship's brain they took aim and hurled him in the mire.
"Upon my word," says Rory, "Wasn't that a splendid crack,
To see Lord Leitrim, Meehan and Kincaid all a-tumbling on their back? "

This old degrading viper deep down in the mire did crawl,
Calling, bawling, cursing God and the boys of Donegal.
To end the joke, his skull they broke and his carcase they did maul,
And in a pool they threw the fool up there in Donegal,

"Well done, my boys," says Rory, as he turned to the sea,
And they got in their little boat that calm at anchor lay.
They paddled their own canoe and they got a speedy shawl*,
And "Hurrah, my boys," says Rory, "For the girls of Donegal!"

Oh, the polismen like beagles gathered round this dirty beast,
And the devils all, both great and small, they had a sumptuous feast.
The haled him down in hell like a bullock in a stall,
And the devils ate him, rump and stump, that night in Donegal.
To me whack fol the dero, fol the riddle dee.

* Several versions concur that the word is "shawl ". Its sense eludes me. Perhaps it has special local meaning?