Thank you all for looking, it’s definitely an odd one isn’t it, at least now I know it’s not just me missing something obvious.
I actually got the birth and death certificates for Alexander who also died in 1856 in the hope of finding a clue. His father registered the birth and when he died in March 1856 Mary Ann Newland registered the death. I don’t believe she was a family member so maybe a nanny or nurse.
The husband Alexander Forfar was an “interesting” character, I did wonder if Sarah left him and he put the notice in the paper for appearance’s sake but maybe that is a bit too far fetched.
Thank you all again for your time and effort.
Pinetree