 In 1941, during the Second World War, clocks were advanced half an hour, to reduce electric power use making New Zealand 12 hours ahead of GMT.This change was made permanent from 1946 by the "Standard Time Act 1945", at which the time at the 180°E meridian was made the basis for New Zealand Time.NZST remained half an hour ahead of NZMT, and the Chatham Islands 45 minutes ahead of NZST.