M.85
It wouldn't make any difference, as QNH is measured at the airfield, then adjusted (using ISA) to sea level. Thus it reads airfield elevation at touchdown, as the altimeters are calibrated to ISA too.
The TEC is designed to account for the anomalies in altimeter readings when in the air above an airfield. In this instance the atimeter in calibrated in ISA, but the atmosphere between the airfield and the aircraft is not!