My agency provided my prospective employers with a SENTENCE just confirming the dates I worked for them and my position. When some prospective employers mentioned that the agency's reference wasn't enough and I needed to provide a third referee, I then asked the agency why did they offer such a reference after I had worked for them for nearly 3 years and at some point I was on a long term assignment for a year. The answer was that agencies are no longer allowed to offer references but to only confirm employment only since they wouldn't observed supply teachers at work. Since I cover different schools on a day-to-day basis. Is it acceptable to request a reference from school heads I have been to their schools on more than one occasion - (if I have been to a school for more than 7 days/occasions in total over a term covering different classes each time)? Will such a head accept that? At some schools I hardly have a chance to chat with the heads though I would have put an effort to feedback to them after a day's work [reason: bureaucracy - and at times will be told 'head is too busy']) .