Jenny - dig this one out before it seeds. It is a native to south america - doesn't like the frost but does spread once established. I suspect it was introduced to the Red hill area by Charlie Russell either in hay or cows that he brought down from a property in northern NSW that he also had an interest in
Thanks Michael, Have dug it out . It came out easily and was only a single plant but will keep an eye out for others which may be out there. Nice to see lots of Wahlenbergia flowering through the area after the rain.