Peruvian apple cactus

Jolly, this area is a desert for most of the year and cactus grow wild here but not very tall due to the strong winds and lack of soil around the rocks. This one does not blow over because our neighbour has tied it to a tall tree to stop it falling. The flowers are out of reach.

I think the reason why it does not bear fruit is because its pollinator is not present in your locality. Maybe you could try to manually pollinate it and see what happens. Another reason could be the climate or zone you are in. Remember that cactus are desert plants.

I looked again today (18 Nov) and all the flower stems have fallen off and no fruit at all.

Thanks for the suggestion Seema. It could be that but I have never seen any fruit on it and I have been looking at it for 6 years at least! We asked our neighbour (it's in his garden) and he said it just grew there! We know his daughter keeps loads of cacti but she is rarely there now.