LONDON (Reuters) – Britain’s independent adviser on ministers’ behaviour said on Tuesday that Prime Minister Boris Johnson must explain why he has not broken the ministerial code after being fined over attending a party during the COVID-19 national lockdown. It had previously been expected that ministers who breached the guidance would be dismissed, but the government last week redrafted some of the rules to reduce the potential sanctions for those who break the code. “In the case of the Fixed Penalty Notice recently issued to and paid by the prime minister, a legitimate question has arisen as…