Robertson arrived at 37 Glassford street in 1866, so this first cdv is probably of this date, with the hastily corrected address. The second, with the address amended, could be from the first card order at the new address in the same or following year. It is a significantly smaller size.
The first cdv below has a type of design that was in use in the mid to late 1860s, so can only be a year or two later. The melancholy man in the second below probably had this portrait taken in the early 1880s, judging by the light filigree design on the back and the name tending towards the diagonal. Robertson was at Comely Bank in Dumbarton between 1873 and 1886.
The cabinet card below probably belongs to the mid 1880s with the Dumbarton address and exhuberant high Victorian reverse. The card backing is supplied by Marion & Co., one of their a standard designs, and carries at the bottom left corner that company name surrounded by the cryptic punctuation marks which have so far defied interpretation.