In 1894 the London Building Act changed the regulations so that windows did not have to be to be flush with the exterior wall. This enabled windows in the capital to stand proud from the facade. The late Victorian and Edwardian period took advantage of the change in new building regulations and now presented their windows in bays.
Interestingly the plaque above the top window states the house to have been built in 1893, before the regulations changed. Although bay windows were possible else where it wasn't until the regulations changed that they became popular on general houses. The ground floor bay window must be a very early example of the form and has brick mullion pillars rather than the more usual slimmer timber ones seen on other local houses and those in the same terrace row.