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During World War I, the palace, then the home of King George V and Queen Mary, escaped unscathed. Its more valuable contents were evacuated to Windsor but the royal family remained in situ. The King imposed rationing at the palace, much to the dismay of his guests and household. To the King's later regret, David Lloyd George persuaded him to go further by ostentatiously locking the wine cellars and refraining from alcohol, to set a good example to the supposedly inebriated working class. The workers continued to imbibe and the King was left unhappy at his enforced abstinence. In 1938, the north-west pavilion, designed by Nash as a conservatory, was converted into a swimming pool.

In what year was the north-west pavilion turned into a swimming pool?
1938