Labour went on to win the 1950 general election, but with a much reduced majority of five seats. Soon afterwards, defence became a divisive issue within the party, especially defence spending (which reached a peak of 14% of GDP in 1951 during the Korean War), straining public finances and forcing savings elsewhere. The Chancellor of the Exchequer, Hugh Gaitskell, introduced charges for NHS dentures and spectacles, causing Bevan, along with Harold Wilson (then President of the Board of Trade), to resign over the dilution of the principle of free treatment on which the NHS had been established.
Try to answer this question if possible (otherwise reply "unanswerable"): What was not a principle the NHS was based on?
unanswerable