Many thanks for that information, Throth
I came to the same conclusion about the reference to Collace, that it's a red herring. Elizabeth's baptism is the first one on the page, and all the children which follow are baptized by the Minister of Perth. So as you say, it's very possible that the Minister of Collace was standing in for the day. Also, I have searched the statistics for Collace and found that there were no fishermen in the village (OK, a bit later, in the 1790's, but one would think that maybe the father or one of the sons would still be a fisherman).
Similarly I have scoured ScotlandsPlaces but found no obvious reference to this family.
I've gone through the Perth burials but there are so many Robert Robertsons that, without knowing about how old Robert might have been, it's a pretty hopeless task. and without knowing when he got married to Elizabeth Stewart, I don't know if there were more children before the ones I have found (which makes it uncertain what the parents' names were).
They were obviously married somewhere! I am wondering if the names have been badly transcribed in some record or other.
Oh well, I have got a lot further back with this branch of my tree than I ever thought I would be able to, and I still have to follow up Elizabeth's siblings, which should be fun
Thanks again, I will keep looking and will let you know out of interest, if I do find anything out, though if you who are experts in the area can't, I don't hold out much hope of success.
(There are some more baptisms on the page I purchased from ScotlandsPeople which I am happy to forward to anyone researching the families:
Andrew Scott (John Scott/ Janet Laurence)
John Archer (Peter Archer / Margaret Gow)
James Honey (John Honey / Mary Scott)
John Constable (John Constable /Catherine McKinnon)
Best wishes and thanks again
Bev