Why has Martin McGuinness of Sinn Fein resigned as deputy first leader of the Northern Ireland assembly?
He resigned because he said the first minister, Arlene Foster, had a conflict of interest over a scheme to subsidise the use of renewable energy in Northern Ireland which has overrun its costs. He said Mrs Foster's party had been arrogant over the matter and called on her to resign. Because of the power-sharing arrangement in Northern Ireland his resignation will probably mean an unexpected election.
What has David Cameron's former aide Steve Hilton said about the prime minister resigning?