I just had a conversation with a caregiver about cats in her area. She told me that a few years ago the TC had asked for a census of the number of cats in her area. She was worried that they might be angry that she had too many cats so she under-estimated the number. I am sure that some people have a fear that the cats will be caught so they tend to under-estimate but the problem is that it may have the opposite efect - ie the TC comes down and realises there are FAR more cats in the area then was originally reported and ask why sterilisation is not working.
For example, in this woman's area, she put that there were 8 cats in the area. In reality, it's one of those long blocks, and she has 20 cats there now. Fortunately no one has complained, but if someone did and the TC came down to do a head count, it's not going to take a genius to realise the number has increased. What this is going to show is that sterilisation is NOT working - because otherwise, how would there be such a huge increase in the number of cats?
TCs will always come up and tell you that you should have a small number of cats - ie they normally will tell you that you should only have X number of cats in a block. However, if you let the town council know that this number cannot be specifically allocated, explain the vacuum effect to them, and let them that the best way to control the cat population is to let it even itself out.
Artifically setting the numbers means new cats will just move in. An area cannot accomodate too many cats once the cats are sterilised - even in a study done in an UNsterilised area, there was a point whereupon new cats moved on because it was too crowded, even though there was food (but in an unsterilised colony obviously to reach this point is much, MUCH later).
Not every TC will ask, but if they do, the important thing is to get your TC to be realistic. 6 cats ALREADY in the area cannot become 2 cats just because they want it to be so. Even if they do, new cats will just move in again and take the now empty spaces in that colony. At the same time, don't over-estimate. It could be doing the cats a lot more harm than good.