Well, with the addition of the "Esq" after his name, I think we could assume that Angus McRitchie was either rich (and therefore a "gentleman") or a professional of some sort. "Esq" was not bandied about back then -- there was a degree of entitlement involved for it to be used, and this was a convention understood by most people.
Assuming he lived in Nova Scotia, we do not know exactly where; "Mc"s and "Mac"s are very common in the province, and Angus is also a fairly common Scottish first name, so his name, altogether is almost as analgous as "John Smith" is in English settlements. I am sure that a look through the census rolls around this time would produce numerous Angus McRitchie's.
Luckily, the 1891 Census is online and is searchable. Guess what? Only 1 Angus McRitchie in all of Nova Scotia. He is listed as being aged 50 and living in Englishtown, where he worked as a farm labourer:


Additionally, the Nova Scotia Archives has, among its collections photographs of one Clara Dennis, who was, assumably a photographer of note, and here is a picture she took of Angus McRitchie of Englishtown:

Could this be the Angus McRitchie in question? It is possible, but perhaps unlikely.
The only other Angus McRitchie in Canada at the time is a 5 year old boy in Compton, Quebec, so I doubt it's him.
The only other possibility is that McRitchie was from Newfoundland, which was not yet a part of Canada in 1892, or perhaps he was living in the U.S. The unfortunate thing is that we do not have the rest of the address, so I guess the question could now be, "Where did the 25 centime rate pay postage to from SPM?"
Incidentally, most SPM stamps from this timeframe are quite rare. This particular stamp is listed at
http://www.allworldstamps.com/count....asp?cid=281 (which uses SG numbers)for L.10.50 in used. Five of them would give you L52.50, but there may be a premium for the five on piece, especially since it appears you have a strip of five with gutter attached.