The Scottish Gaelic lyric in question can be viewed on the thread for Songs about Nurse Edith Cavell. I'm starting a separate thread so that some effort can be put into translating from the Gaelic into English.

It is a fact that Malcolm MacFarlane's text, written in tribute right after Nurse Cavell had been put to death by firing squad, became part of a publication from Eneas Mackay in Stirling. The "Lament," published as sheet music, states that MacFarlane wrote the melody and the Scottish Gaelic; Murdoch Maclean wrote a singable English text to fit to MacFarlane's melody; and Arthur W. Marchant, Mus. Doc. (Oxford if I recall right), harmonized the whole thing with a keyboard accompaniment.

I want to leave Maclean's English out of this, no disrespect intended, but the English translating requested here ought to be literal, for people like me who are complete outsiders to Scottish Gaelic.
Also, it is my suspicion -- there is no way to prove this, that I can think of -- that MacFarlane's Scottish Gaelic came first, with its references to Herod and Nero and shameful villains and so on. Maclean's English, my guess again, might have been written later, and is all about having something in English to sing in, thus Maclean was not required to literally translate everything in the Gaelic.

Hopefully any posts to this thread will result in something that can then be posted to the Nurse Edith Cavell thread when it is suitably polished up.

The Gaelic is coming in my next post. Thanks all for your patience.