iPad 2 AirPlay button has disappeared

I work in a school that uses 130+ iPad 2's and 10+ 3rd Gen Apple TV's, 130 2nd Gen iPad's are used by pupils are running on iOS 9.2.1 and the Apple TV's are running on 7.2. The iPad 2's have no AirPlay button on the control centre at all. I have tried relentlessly to fix this issue, hard reset both iPad and Apple TV, tried running Apple TV through ethernet and wifi to no avail, made sure both are on the same network, trawled the internet and tried all the quick fix suggestions such as change language, turn on airplane mode etc. Now the strange thing is that iPad Air's and iPhone 5's and above work flawlessly with Apple TV so this leads me to ask the question have apple changed something that no longer allows iPad 2's to use AirPlay to mirror?

I've tried speaking to Apple directly and all they give me is the usual IT spiel "Have you tried turning it off and on again". I'm going to take the Apple TV unit and an iPad 2 home with me tonight to see if it works in a home network environment. Any help is appreciated!