The QNE is the reading in feet on an altimeter with the sub-scale set to 1013.2 mb when the aircraft is at aerodrome or touchdown elevation.
Is there an equivalent Q code for other altimeter settings when the knob comes off in your hand...?
Oxford once kindly calculated the circuit altitude and landing altitude for me when that exact thing happened when I tried to set their QNH. I was previously on Cranfield's (not 1013.2) so they had to do a bit of maths...
Tim