Could someone help me identify this plant on the below mentioned link?

http://sendall1542.fotopic.net/c583728.html


The plant is about four foot in height, the flower petals are a purple
colour, star shaped and only appear to open during the morning period, the
stalk and leaves are not unlike the leaves and stalk of Pinks but greener
and larger.

The plant appeared in my neighbour's garden, we are all mystified,

Thanks in anticipation,

Bob