Dear all, this is an open apology! The spurious verse about the McDonalds had been ringing bells for a few days so I searched through a compilation of one hundred songs I had put together in 1964 for publication by Scott Solomon. Under 'Bonnie George Campbell' I found verse 4:

Ower the howe rade MacDonald the Reid,
An tied tae his saddle was Campbell's black heid;
The blood frae its open mooth ran tae the grun'.
"Revenge!" cried MacDonald, "Revenge for my son!"

So I guesse I'm the culprit for such a dreadful verse!
Apologies again, I can only put it down to youthful ignorance.
Jim McLean