I have no particular knowledge of these three schools, but the number of children registering for the 11+ in Aylesbury is actually down! (1719 in 2006, compared with 1803 in 2005, and 1816 in 2004.)
However, the qualification rate, historically low in Aylesbury, has improved a bit. (The latest figure for 2006 is 368 children qualifying, compared with 354 in 2005.)
In the past I assume some of the slack at grammar schools in Aylesbury has been taken up by children with high scores from outlying areas such as Milton Keynes. Under the new admission criteria, children who live closer to the school should be at an advantage.
There is always the risk of insufficient places for late appeals and the 12+, but Bucks is to be congratulated on completing all timely appeals by mid-February, so that successful appellants can be included in the first round of allocations. (Many other authorities with selective schools have not done this.)
In the grammar allocation the main pressure spots have been Beaconsfield High and Dr Challoner’s Grammar, with all other grammar schools taking all in-county catchment preferences.