^"Brown move to cut UK nuclear subs". BBC News. 23 September 2009. Retrieved 24 January 2011.
^ Taylor, Adam (13 July 2016). "Every new British prime minister pens a handwritten 'letter of last resort' outlining nuclear retaliation". Washington Post. Retrieved 13 July 2016.
^Rosenbaum, Ron (January 2009). "The Letter of Last Resort". Slate Magazine. Retrieved 18 May 2009. In the control room of the sub, the Daily Mail reports, "there is a safe attached to a control room floor. Inside that, there is an inner safe. And inside that sits a letter. It is addressed to the submarine commander and it is from the Prime Minister.
^ Rosenbaum, Ron (January 2009). "The Letter of Last Resort". Slate Magazine. Retrieved 18 March 2012. [E]very prime minister in recent years has written such a letter and ... letters that go unused (Tony Blair's for instance) are destroyed without being read.
^ Norton-Taylor, Richard (11 July 2016). "Theresa May's first job: decide on UK's nuclear response". the Guardian. Retrieved 13 July 2016.
^Goodall, David (26 May 1983), Arrangements for briefing a new Prime Minister in the event of a change of administration following the 1983 General Election (PDF), TNA) (published 1 August 2013), CAB 196/124, retrieved 5 September 2013