Thank you, Goosepimple.
I do think farm cats are pretty healthy with living outside. We have never had any serious illnesss, other than the ones with the wheezy chest. Sometimes they are limping, which is likely to be either a nail caught on something they pounced on to catch, or maybe a stone off the dry stone wall landed on their foot, but they come right, and we have the usual torn ears where the toms have been fighting. When they have coughs and colds, they curl up in the old caravan where they live, and go to sleep for a few days!!
I do manage to worm them - if you can imagine lots of dishes lay out wth cat food on, and wormer hidden among it. They are crafty though, and will not eat the tablets, but can usually get away with powder if its well mixed, or the liquid. As to fleas, I spray all their bedding, and them too if I can get near enough!!! The friendly ones, I do spot on on their fur.