christgill beat me to it. I also have the earlier 1894 OS map which shows the same thing but the housing on Carholme not yet having been built. The map also includes entries apparently from the Kelly's Post Office London Directory 915 (not sure why such a later date). This has the house as being no 300, registered to a Duisberg Trougott Geo florist (named Duisberg T George in the 1914 map) and no 302 (the Willuam Hill building) registered as Stanstead Park Nursery. Though the house numbers are slightly different to today, the cross streets are given, so they do refer to this house and building which when I look on google maps do look like they are of the same brick.