Does anyone know...?

[L Verge]

The more I look at the engraving from Leslie's, the more I'm inclined to think that the short, middle "building," in front of which the man stands, is actually a gated area that is wide open space between the stable to the left (flat roof) and the "carriage house" to the right (more peaked roof). The buggy and the horse were in separate shelters with space between for entry and exit - and a locked door for security. Just one "shed" would have to be big enough to hold a horse (pretty big creature) and a buggy (they're pretty large also, even a two-seater).

There were buildings in that alley that also housed alley dwellers (very common in DC and most large cities). You see those in one of the displays on BoothieBarn. Spangler was both keeper and protector of that horse and buggy, probably; however, John Ford said that Peanuts was the hostler.