Thanks Mabel
like you say, there are a number of possibilities - and, tracing them through the later census there are, alas, a number of people with the same name born in the same area at the same time, meaning it is impossible to nail down which ones it could be. I am beginning to wonder if it might be one of the girls having the children 'on the other side of the blanket'....but it is just assumptions.
Really hoping someone might have the fiche for the Ketton PR which might but the mystery to bed without me having to get birth certificates for Robert John and Agnes M...