That's absolutely correct. It is 120 (standard admissions) and additional 4 on the basis of academic ability and tenure of a Wakeham Choristership at the Queen's Chapel of the Savoy. Apologies from me as well for hijacking the thread
On the original question - you give the preferences on CAF, council looks top down to assess your suitability and seat availabilty. The moment your preference match the criteria, they allocate you a place and stop.
I think for St. Olave's in particular:
* Likely is 100% (subject to CAF)
* Possibly is 50-50 (subject to CAF and other people leaving spaces)
This means if you have got a "likely" letter and have put that as first preference in CAF then you should get it 100%. Otherwise there is no point distinguishing results as likely & possibly.