Maybe it's called Three White Horses?

Or perhaps this is n't the one you're referring to:

SEE THAT MY GRAVE IS KEPT CLEAN
(TWO WHITE HORSES)

Traditional (as sung by Hobart Smith)

Well, it's one kind favour I ask of you (3)
Please see that my grave is kept clean

It's a long lane, ain't got no end (3)
It's the longest lane that's ever been

Three white horses in a line (3)
You  may let me down with a golden chain

Dig my grave with a silver spade (3)
You  may let me down with a golden chain

Did you ever hear a trumpet sound? (3)
You will know the poor boy's in the ground

Did you ever hear a church bell tone?
You will know the poor boy's dead and gone

Regards,

A