Letters of last resort written by Theresa May will contain orders on what Trident submarines are to do if a nuclear strike has destroyed the United Kingdom.

Theresa May is the new Conservative Party leader and will become the UK’s second female prime minister today, taking charge at one of the most turbulent times in recent political history.

The letters of last resort are stored inside two safes in the control room of each submarine. The letters are destroyed unopened after a Prime Minister leaves office, so their content remains known to only them.

The United Kingdom relies on four Vanguard-class submarines to provide its nuclear deterrent. At least one submarine is always armed and on active service, carrying 16 Trident II submarine-launched ballistic missiles each with a range of 7000 miles, and 12 independently controlled warheads each capable of destroying a large city.

According to the December 2008 BBC Radio 4 documentary The Human Button, there were four known options given to the Prime Minister to include in the letters of last resort. The Prime Minister instructs the submarine commander to:

  • retaliate with nuclear weapons;
  • not retaliate;
  • use his own judgement; or
  • place the submarine under an allied country’s command, if possible. The documentary mentions Australia and the United States.

Former chief of defence staff Lord Guthrie said that Tony Blair “went quiet” when he had to write the letters.

In a BBC Radio 4 documentary, Lord Guthrie said:

“I think quite honestly, like most prime ministers, he hadn’t given a huge amount of thought to what this really meant. And it is actually an awesome responsibility.

It really comes home to you that he could, if the circumstances demanded it, create devastation on a huge scale.”

Writing the letters is one of a number of protocols that May will likely complete today.

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Lee Seward

How does the letter get delivered to the one sub that is out on patrol?

David Hollingworth

Always one of a PM’s first tasks. But what about the sub that’s currently on patrol?

Callum Sweeney

Suppose they can just get it via signal

Tom Crawford

I doubt they would receive it by signal, they are handwritten and not to be opened unless the Commanding officer of the sub has determined that the UK government no longer exists, it may be that a tender servicing/supplying the sub will give the letter to it.

Ray Lovie

Tender ……you do know what patrol means once leave wall and past 200 m mark we are ghosts

Kyle Greet

As I understand it, the previous PM’s order remains in force until that submarine returns to Faslane.

Peter Vine

Peter Hennessey’s “The Secret State” is required reading for this sort of thing. As Kyle says, the previous PM’s order remains in force. When the sub returns the old orders are burnt.

Peter Vine

Also the stress test for determining if Britain still exists or not is to check for the BBC world service.

Liam Fowler

Out of curiosity, which option would people choose?

James Thame

Place the submarine under allied command

Jason Atkin

Target Donald Trump

Clark Mccarron

Target all known enemies of the empire of great Brit and wipe them from the earth for striking us then head to Australia

Fire everything at Yellowstone & wipe-out whatever of humanity was left in a supervolcanic eruption ?

Simon Robinson-Lovatt

Letters are hand delivered, sealed and put right into the safe so as to ensure nobody can snoop at the letter before it’s secured. The old letter… is it destroyed or archived?

James Thame

They burn them

Ray Lovie

Their burnt

Carl Vincent

Very interesting

Ray Lovie

Boats subs are sandwiches agggggh

UK Defence Journal

Subs is a better choice for a headline, more people associate it with submarines.

Ray Lovie

Boats are better ….

David Alexander Harrison

Yeah, submarines fall into the category of boats not ships, but they *are* submarines – that’s not some made-up term – so calling them “subs” for short is entirely valid…

Carl Vincent


Gav Mcinnes

Keeping Britain Safe!!! Massive respect to the men and women who man our Nuclear Deterrent.

Daniel Meredith

Chris Mornin pretty good read

Peter Vine

I believe no PM has ever revealed what they wrote.

Kyle Greet

James Callaghan did, he said he would have retaliated.

Peter Vine

Ah yes, he actually revealed that the Henessy as well in an interview in 1988.

David Timothy Lee

Make it rain!!!!!!!!

Steven K

Guys, to think this man had the red button at his disposal is frightening.

Must see


Truly astonishing, Obama has his critics but he’s cool as feck. Michelle’s clenching her hubbies fist in disbelief while Bush’s wife is probably whispering get it fuc…g together man!

Muhahahahaha! Bush’s best yet.

Harry Bulpit

“Not retaliate” if a MP gives that what’s the point in having it? And can it only be used once the UK has been blown in to pieces? Can a MP order its use in another sercmstance?


I can imagine Thatchers being something as simple at “Strike back.”