We did go to City Hall. The CM kind of shrugged his shoulders and said we shouldn't have left our things outside, he checked to see if anyone had handed her clothes in, but to no avail. We did think that after finding 'second-hand' clothes the crook might have just dumped them.
We went back to City Hall just before we left and they gave us a phone number for us to try again today.
One lovely CM, when hearing our story, went and got a new balloon for my daughter to cheer her up as she was quite upset that someone would steal her clothes.