The country’s top civil servant said Boris Johnson was “mad” if he did not believe his private WhatsApp messages would become public as part of the UK Covid-19 Inquiry.It comes as a former top aide to Mr Johnson suggested he was worried about leaks from the heart of Government, amid questions about why he had turned on the “disappearing message function” on a WhatsApp group in April 2021.Martin Reynolds also made repeated reference to former chief adviser Dominic Cummings – due to appear before the inquiry on Tuesday – and the “unusual dynamic” he brought to Downing Street.