Thanks everyone for your replies.
@Sneaky Cuttlefish - no they are yet to product any fruits, I have been watching closely for 6 months, and thought it was meant to happen after flowering but we got nothing. Thanks very much for your advice, I will give them a spray and a brush and see how it goes.
@Cereoid - I'm not sure what an ovary and style are, but I can tell you that yes the flowers dropped cleanly, leaving behind a small dark round bit with a stringy bit hanging out. Hehe is that an ovary and style? Thanks so much for your advice and input, I will take a close up over the weekend and will post a photo of the green/yellow patches, would love to get your thoughts. I will also give a tug to the badly damaged columns - thanks! Good thinking...
@Supergirl - thanks for your link and for the advice, I wasn't sure how quick they grow but would like to do what I can to save them. I will give your suggestion a go. I get the impression that cacti can be difficult to ID properly so I really appreciate all input.
Does anyone know how frequently ones like this tend to flower? Also how quickly they grow?