This happened to me three years ago when I was heavily pregnant. I too was conned and gave her ?10 and the minute I shut the door I realised I knew the people at the house she was talking about. The funny thing was a few weeks later she rang my doorbell at 10am on a Sunday morning and had a child with her, around 6 or 7 years old. I thought I was wrong about her as I thought she was going to give me my ?10 back. Oh no, she tried the same scam. She had completely forgotten she'd been at my house a few weeks before. I told her this and she denied coming to my house but never denied living down at the certain house.