It's a Stapelia gigantea!!!

This plant has been growing for a year - and I've narrowed the identification down to Stapelia grandiflora and Stapelia gigantea.  The other plant bloomed steadily about two to three months ago so that kinda out ruled grandiflora.  The flower buds have been forming now for a few weeks and yesterday the first one popped open!

Closure is a good thing!