Boyd-RobertsonOK - I think I've found a connection, but still don't know if they tie in to Allan Robertson's family. Here goes:
Thomas Boyd married Mary Dow 20 Aug 1781 Ardrossan, Ayr. Their children:
Helen Boyd - chr. Greenock, 23 Oct 1787
Thomas Boyd - chr. Greenock, 16 May 1790
Jean Boyd - chr. Greenock, 14 3 1792
Mary Ann Boyd - chr. Greenock, 20 Aug 1794
James Boyd - chr. Greenock, 28 Jun 1796
Margaret Boyd - b. Greenock, 26 Aug 1798
Agnes Boyd - chr. Greenock, 31 Mar 1801
Bethia Boyd - chr. Greenock, 15 Jun 1803
Margaret Boyd - right kind of age and birthplace to be the one who married Archibald Robertson in Greenock on 15 Feb 1819.
Agnes Boyd - an Agnes Boyd married John Robertson in Greenock on 19 Oct 1824. This would make her a good candidate to be William Wood Robertson's aunt Agnes Robertson on the census entry. Age and birthplace fit.
Questions!
1. Are Archibald and John brothers? Agnes would still be WWR's aunt even if the 2 Robertsons are unrelated!
2. Are these Robertsons part of Allan's family?

3. Is Thomas Boyd related to David McIver's wife, Jane Boyd?
Rambler