I cannot find a mention of this on any modern atlas or map, book or online. A 1950s atlas of London mentions Bridport Street, NW1, too small to be marked but close to Broadley Terrace, which still exists.
Here
http://london1868.com/weller27.htm above Blandford Square, you can see these, Bridport Street running North - South, Broadley Terrace west - east.
There's no mention of Bridport Street on this
http://www.rayment.info/general/road_name_changes/index.html list of London street name changes, so I assume the street has been demolished / re-deveoped.
Hope this info helps.