Continuously at sea on deterrence

About 6pm last night after nine months of agonising over the nuclear deterrent and whether to go for four or three subs, Ed Miliband folded to pressure from the older hands in the party and went for four. There was some wrangling later on over the wording of the statement, figures close to Ed Miliband hoping to retain some wriggle room … but the shadow defence secretary Jim Murphy announced the four-sub policy this afternoon in definitive terms.

So the prospects of the Lib Dems getting to end continuous at sea deterrence  look mightily reduced. You could imagine them trying to foist it on Labour in a coalition negotiation (with some close to Ed Miliband quietly hoping it’s a good moment to junk four subs). You could also imagine some Labour big names fighting back and making Ed M stick to the existing line.

If he becomes prime minister, Ed Miliband will get a visit from the first sea lord on day one to go through the nuclear weapon firing command chain. As prime minister, he writes a “letter of last resort” to be deposited in the safe of a submarine  – there’s a fascinating BBC Radio 4 discussion about it here . In that programme, figures compose their version of the letter.

I understand that PMs are presented with a draft letter that the Royal Navy has prepared. The idea – central to continuous at sea deterrence – is that the letter is signed straightaway and put in an envelope that is then sent to sit in the safe on whichever Vanguard submarine is at sea.

Senior naval sources say there have been a couple of prime ministers who did not sign straight away. The letter sat in the No 10 in-tray as they pondered, maybe had a few sleepless nights. I’m not sure whether that counts as a break in continuous at sea deterrence.

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