It looks like the source of last week’s leak of the Government’s plans for the Huawei issue was the Defence Secretary himself.

The leak, which was published by The Telegraph, revealed that the UK government is planning to go against US advice and allow some Huawei kit in non-core parts of the country’s 5G network. The US reckons any Huawei gear constitutes a potential security risk and has indicated it will cause diplomatic problems if any of its allies don’t do what they’re told on this matter.

This was one of the main reasons why the leak was such a problem for the government, which immediately launched an investigation into the source of it. That investigation apparently concluded it came from the UK’s most senior security professional: Gavin Williamson, the Secretary of Defence. Prime Minister Theresa May consequently had no choice but sack him.

You can see the official government statement and May’s letter giving Williamson the boot below. Williamson hadn’t made any public comment at time of writing but it’s hard to see any possible mitigation for leaking information from the National Security Council.

UPDATE – 19:00 1/5/19: Williamson has responded, here’s his letter.