Here's George Robertson's family in 1861, living in Toxteth Park, Liverpool:
RG9/2707 - Folio 69 - Pg 31
George Robertson abt 1820 London, Middlesex, England Head
Mary Walker Robertson abt 1822 Port Glasgow, Scotland Wife
George Wood Robertson abt 1852 London, Middlesex, England Son
David Robertson abt 1854 London, Middlesex, England Son
Charles Wood Robertson abt 1856 London, Middlesex, England Son
John Wood Robertson abt 1858 Liverpool, Lancashire, England Son
David Gilkison abt 1820 Port Glasgow, Scotland Visitor
Mary Ann Jones abt 1840 Mold, Wales Servant
Sarah Catherine Money abt 1838 Monaghan, Ireland Servant
Alice Jane Wilford abt 1838 Doncaster, Yorkshire, England Servant
So this part of the family moved from London to Liverpool between 1856 and 1858.
The name Robertson is more common in Scotland than England - we seem to have a Scottish connection here.
MR