Great Aunts bathing beauties

These were sitting on my Great Aunts window sill until she passed away back in 1986. They were passed down to me, as they were going to be thrown out. They've been in storage for the last 20 years. I have no idea as to how long she had them, or where they originally came from. (Only that the family immigrated from the UK to Australia in 1907, when she was 17). My great uncle had put felt on the bases so they wouldn't scratch the window sill. I've just managed to peel this off in hope of finding a pottery mark. Unfortunately, there isn't one. There is only what appears to be either "+557." Or "4557." On the back of one of these. They are approximately 12cm wide and 8cm tall. Any clues as to where these might be from, or their age would be appreciated.