BHS has extended to "All Offered" only twice in recent years - this year and in 2009. You can see the past Allocation Profiles here: http://www.elevenplusexams.co.uk/school ... n-profiles
Please don't pin your hopes on getting a place at the school. With a new Head and with things moving forward after a few problems (not academic ones) I suspect it will become more popular.
On a more general note ...
The vacant places are for this year's Y7. Any applicant wanting to take advantage of the vacancies can call the school in the first instance, but ultimately they must apply to Bucks CC for late testing. The late testing procedure for this year ceases in July, and can be very tricky to navigate.
BCC specifies that it is for (my words) children who have moved into the area after the main testing process has been completed. It isn't easy to overcome that stricture unless you have, quite genuinely, moved into the area since October 2011.