I found a residential and business directory for Inverness for 1935-36 online.
It confirms A Munro, butcher, at 16 Innes Street (which was a residential street of houses). But none of the many butchers' businesses in the town had "Munro" in the name, so I guess that at the time he was working for one of them.
Buying a van or two is the sort of thing you would do if you were starting up your own business, so finding a business directory for 1938 or 1939 could be very useful. (Later addition: Duh! I've just seen that the directory that IBM linked to lists businesses as well, on the appropriate streets.)
Similarly, copies of the "Inverness Courier" for that period - which are not online, AFAIK - might carry adverts for the business, though perhaps just a few, around the time of startup.