I am just curious, but how does this work? I was talking to another mum and she said that her year 7 son was lucky to get a place at his school. He did not get a place initially because he was "out of the catchment area for his ability group". He was lucky with the waiting list. She said that this particular school is very oversubscribed particularly for the upper ability group.
I know that SATS results are not out when secondary places are allocated, and I would be surprised if a comprehensive school had it's own test. Years ago when I was a child, we all sat a test in the 4th year juniors (year 6) and were given band 1,2 or 3. I thought all that had been replaced by SATs, and the catchment area of a school applied equally to all children. It seems I have a lot to learn