This is what I got told the other day is the CIE to be installed in the protected area, not visable from outside of the protected premises.
Someone did ask about combined keypad and CIE and was told this would be ok to fit on entry route but is down to the risk assessment.
I assume its in the BSEN50131 or PD6662
but looking at at lest two places i have been in one CIE was mounted above the entrance door with the keypad next to the door. and the other was mounted on the right hand wall as you go in with the keypad on the left. So i would think this might be something thats been put in to the regs in the last few years.
But I could be wrong and shot down in flames and buried alive.