I had all my female cats speyed on a cheap scheme runnng at a vets about 12 miles away. Then someone dumped some half grown cats who were female. They are feral, although come when I go to feed them, there is no way they will be caught. We tried a trap, and just caught the greedy fat toms, who I can actually pick up anyway!!! The RSPCA gave me neutering vouchers - just a matter of catching them now. Even if I shut them in the cupboard with the kittens, I still have to somehow get them out of there - and when trapped they use their claws, teeth, anything to avoid capture.
We have no trouble finding homes for the kittens, which I handle every day, to make sure they are tame before they leave.
I have 9 cats at one farm all speyed plus two toms who are not mine, but sort of lodge with us then 8 at the other farm, although to be honest, they are pretty independent, hunting mice and rabbits etc. I go down twice a day and put plenty food and biscuits out in their caravan though. Even though they are feral, they will not be left behind when we move, I could not do that, in case the new owners did not feed them!!