Our Robertsons:
Allan (starting point) - b. 1872, Camberwell, Surrey.
Siblings: Claude (b. 1867, Peckham, Surrey) and Margaret (b. c1877 Camberwell)
Possibly 2 more siblings b. Scotland
Allan's father - James Robertson, b. c1843 London. Married Mary Marshall Molison in 1866. Died before 1881 census.
James had 2 brothers (or half-brothers):
George Robertson, b. c1820, Wapping. Married Mary Walker Gilkison in Port Glasgow in 1849. Known children: George Wood (c1851), David (c1853), Chales Moodie (c1855) and John Wood (c1857). (NB: middle names "Wood" not very clear on census image - may be something else.) George was a ships chandler, followed into the business by son Charles. David set up on his own account in London as a sail maker. George moved from London to Liverpool c1856.
John Robertson, b. c1834, Limehouse, London. Married Augusta Jane Molison in Worthing in 1858. (NB: Augusta Jane was Mary Marshall's sister, ie. 2 brothers married 2 sisters.) Known children: George Douglas (c1860), Augusta (c1861) and Mary Douglas (c1864) - all born Bromley.
These are the only confirmed members of our family, as I have tried to point out several times! (No, I'm not getting ratty, but I honestly don't see why we should be following anyone else without something concrete to link them to the list above....)
There is, however a Colin Robertson with a very similar background, who might be a brother or cousin to James/George/John.
The Mary M Robertson b. Canada has no proven link with either "our" Robertsons or the Molisons.
I'm sorry if I haven't made the summaries clear enough, but I'm doing my best....
Rambler