Most of the photos that I have seen by GR Mackay are postcard
portraits from the period 1909 to 1921, from his studios at 25 North
Bridge and 70 Leith Walk.
However, the carte-de-visite above is from his earlier studios at 105
South Bridge, where he was based from 1902 to 1908, towards the end of
the cabinet print and carte-de-visite era.