I think you have to remember that this is from a census. The enumerator was supposed to enter the county and the parish of birth. If it is from a Scottish census, you would have the parish or N. K. for not known. Sometimes, a town or village, even a farm name appears instead of the parish, if the enumerator was given this and did not realise it was not the parish. Occasionally there is a blank left, but you would not get N.B. for North Britain in a Scottish census. Firstly it was not what was supposed to be written and also there would be no point in wasting space and ink on the obvious. If this is an English census, I can't see why they did not just write "Inverness(shire) Inverness" as they were supposed to.
Graham.