Premiership of Theresa May
Multiple cabinet members resign on the day of Johnson's ascension to premiership, or in the days preceding it, in response to Johnson's politics and views on Brexit, including Chancellor, Philip Hammond, Foreign Secretary, Jeremy Hunt, David Gauke, Sir Alan Duncan, Rory Stewart, Anne Milton, and Theresa May's de facto deputy the: Chancellor of the Duchy of Lancaster & Minister for the Cabinet Office, David Lidington.
Sources: Financial Times The Guardian The Times