Can anybody give me an ID on this pea?

http://box.net/public/richwrig/dfiles/ClimbingPea.jpg

It grows in late winter/early spring (Sydney, Australia) as a climber
up to 3 m (10 feet).

The pods, which are reasonably sweet and tasty, have a peculiar
appearance of being closed by a purplish zipper.

The location is on the edge of a communal vegetable garden but none of
the community is ever there when I pass by.

What is the speciesd/variety? Is it edible?