I know it doesn't conclusively prove my point (I'll have to trawl through some of those old episodes to source some screen grabs), but I just know there some examples to support my argument. I believe this funeral scene is indoors - the cobbles and pavement are painted on the studio floor by the looks of it. Having said that, the fact they've got it raining in this scene is a harder one to explain away, but either they're pouring water indoors or they're super-imposing another piece of film with rain!
Fascinating, Sky! And the pillar box looks wet, doesn't it? I suppose the set was joggled around at times in the early days, but at the time of Ena and Elsie's classic poison pen confrontation in 1961, the bay windows were still joined, as they were on 9 December 1960 for the very first episode (although establishing shots, in reality Archie Street, showed single bays). Albert's disappearing bay window I think occurred at some point during the first thirteen episodes, in a scene involving Harry Hewitt and Concepta Riley. There suddenly seemed to be an alley beside the Rovers!
See Ena, Elsie and the 1961 joined bay windows below in a classic clip from YouTube.