On FindMyPast, I have just entered 1871 and "designer" as a keyword in the census search. 461 entries come up with designer. It is difficult to know exactly what he is designing, but think about what the industries in the area were, what his job was on the 1881 census, what the occupations were of folk in his immediate area. Perhaps there might be a reference to him in the newspapers which would give a hint as to his employment.
