The former head of the UK’s civil service has described the Chinese leader Xi Jinping as a “dictator” and said Donald Trump had put “helpful pressure” on Europe to increase defence spending. Simon Case, who served as the cabinet secretary until December, when he stepped down on health grounds, said China had sent a clear message to “prepare for serious conflict” in Taiwan. The UK has committed to spend the equivalent of 2.6% of GDP in 2027, and it and other Nato members have signed up to increasing spending to…