The info for Dorothy St comes from the Slaters directory of 1911.
There are 4 volumes, one of which lists the streets in alphabetical order, and the householder at each address.
Another one list all the householders in alphabetical order, with their addresses.
It is online along with quite a few others at
http://www.historicaldirectories.orgThey can be a bit of a pain to search, especially if you have a common name, in which case I use the browse function to skip to about the right page and home in.
Cheers,
Dave