In the 1913 Miss Young card (not to be confused with the 1904 Miss Young card which is probably to a completely different person although there seems to be something about that name that attracts problems for the researcher) the address is clearly written but does not seem to exist in the census. Presumably it still got to its intended recipient, but without being able to identify the person, further research has proved fruitless.
Is the fact that it was for 7A significant? Without knowing the type of building it is impossible to say.
This is all particularly frustrating because there seems to be so much going on in this card.