Restoring iCloud Notes

I am not sure that the two are linked but I seem to have lost a very important Note which contained info that I regularly updated across all my devices. Mostly from my iPad, occasionally on my Mac & iPhone.

This note seems to have disappeared and is not in the deleted section on any of my devices. I recently upgraded my MacBook Pro to a new iMac 27" restoring from a Time Machine backup which appeared to work brilliantly apart from this missing note.

Has anybody got any ideas as to where a backup may be found and how to restore a missing note?