Twelve in a row

These twelve chimney pots in a row caught my eye on my walk with Smithers this afternoon. The two houses they belong to are in a road called The Terrace, but the houses in The Terrace are all actually pairs of semi-detached Victorian villas. I love their architecture; they have wrought iron pillars holding up canopies across the front, and I love the brickwork patterns. 

When we got home I looked on Google Street View, and was interested to see that it’s only this particular pair of houses that have twelve chimney pots in a row in one enormous chimney. The houses to the right of it have four chimneys, two at the front on either side and two at the back, each with three pots, and the houses on the left of it have only two pots in each, so I wonder why this pair has a joint row of twelve in the middle between the two houses?