Moss klinging to the church wall. That wall is blackened by years of coal smoke pollution that was burnt on house hearths and to fire up the bottle ovens that fired the pottery made in old factories. In those days I doubt that moss would have grown on the church wall even in Penkhull village which stands on a hill above most of the city. The city has transformed over the years and is now much cleaner.
You can see photos of the hundreds f bottle ovens that crowded the city. The smoke belched out of them. Look up the Potteries Museum and Art Gallery and Gladstone Pottery Museum on the net for more information.