Finally perhaps I have been able to nail Sweet
Karela uploaded by Nabha ji on September 7
It is Cyclanthera pedata
Real Sweet karela is Momordica dioica
Chayote with which Usha ji tried to identify it is
different plant Sechium edule (I have uploaded separately.
Thanks Usha ji for reopening the thread and
suggesting a plant which I had photographed only a fortnight ago, and which
prompted me to do some restudy.