Spot the difference!
Look closely and you will see that each of the upper first floor windows is a different shape to it's neighbours. The theory was, that these former farmers would turn their hand to fishing, The differing shapes would allow the woman of the house to signal her man by placing a candle in the window while he was out fishing in the Firth of Clyde. Sadly, but understandably, most of the dispossessed moved away to other parts of the island in protest against their eviction.