Thank you,ev,for taking the time to help me with this.Ididn't know about the 1881 census - I have been using the ancestry site and it only gave me the years I mentioned earlier,so I was really grateful to have that extra piece to fit in.
A good point about the wife's death certificate - the wording just says "married,John Mckechnie,blacksmith" which implies that he was still alive then,doesnt it?
I have just looked at the marriage certificate for Angus and Mary,and it says,father John Mckechnie,blacksmith, and Mother Jane Christie deceased" - so now we know that John was still alive in 1879. A very good piece of advice to check up on,ev,thank you.
Little John,born 1871 at Milton,according to the 1881 census,is not mentioned at all in the 1871 one,so that is great - another member of the family discovered!Jane must have died very shortly after she gave birth - she had phthisis for 4 months prior to her death - I'm not sure what that is!
Thank you for the extra details you have uncovered,ev,and please continue to help if you would be so kind - I'm so,so grateful for your advice and help,Carolyn