I have tried it on, just in case someone thought it was for me, but alas, it is
No one has knocked on the door to ask if we have found a dress because it got left in our garden by mistake.
I still think it might belong to someone in the street, and they are waiting for a friend etc to drop it off. Maybe they will wait a little longer and then contact the person involved and ask them about the dress. Hopefully that person will then be able to remember where they dropped it off!
If it hasn't been collected or claimed in about 4 weeks time, then I will give it a nice send off to the local op shop round the corner, because it is in wonderful condition and they may as well benefit from it.