This be it, I think ... a poem from "The Ingoldsby Legends". Not a song, unless someone has set it to music.

Smuggler Bill
Barham, Richard (1788 -1845)

Smuggler Bill, he looks behind,
And he sees a Dun horse come swift as the wind,
And his nostrils smoke, and his eyes they blaze
Like a couple of lamps on a yellow post-chaise!
Every shoe he has got appears red hot;
And sparks round his ears snap, crackle, and play,
And his tail cocks up in a very odd way,
Every hair in his mane seems a porcupine's quill,
And there on his back sits Exciseman Gill,
Crying 'Yield thee! Now yield thee, thou smuggler Bill!'
…The dapple-grey mare made a desperate bound
When that queer Dun horse on her flank she found,
Alack! And alas! On what dangerous ground!

It's enough to make one's flesh to creep
To stand on that fearful verge, and peep
Down the rugged sides so fearfully steep,
Where the chalk-hole yawns full sixty feet deep,
O'er which that steed took that desperate leap!
It was so dark then that under the trees,
No horse in the world could tell chalk from cheese-
Down they went- o'er that terrible fall,-
Horses, Exciseman, Smuggler; and all!!