The Liberal Democrats manifesto has made an incorrect point regarding the patrolling patterns of Trident carrying submarines.

This article is part of a series looking at the manifesto claims made by the main parties in the run up to the 2019 General Election.

The Claim: “Maintain a minimum nuclear deterrent, while pursuing multilateral nuclear disarmament: continuing with the Dreadnought programme, the submarinebased replacement for Vanguard, but procuring three boats and moving to a medium-readiness responsive posture and maintaining the deterrent through measures such as unpredictable and irregular patrolling patterns.”

The Reality: The idea of building three submarines instead of four – the minimum number needed to maintain a continuous at-sea deterrent – would mean that patrols are in fact more predictable as there will be long periods in which submarines are not ready to sail. The UK operates four submarines in this role to ensure that one is always available to sail while the others are in refit, working up for deployment and having just come off patrol.

Verdict: Reducing the fleet from four to three boats would not result in anything beyond negligible cost savings for what would be a significant decrease in availability. It is not correct to say that it’s possible to maintain unpredictable patrolling patterns with only three submarines as foreign states would be fully aware of when submarines are in maintenance or haven’t deployed.

What’s the background here?

The Liberal Democrats have often argued that, post-cold war, a four-submarine nuclear fleet is no longer necessary. However analysts argue that four submarines are needed to maintain ‘continuous at-sea deterrence’ – an approach which allows the UK to keep one of the submarines at on patrol at all times, with enough back-up to switch submarines as needed and cover unexpected eventualities.

The UK has already reduced the overall explosive power of its nuclear arsenal by 75% since the cold war. It is also believed that savings to the Ministry of Defence budget might be £3bn to £5bn, and even more in reduced running costs. However, the claim above is that it’s possible to “maintaining the deterrent through measures such as unpredictable and irregular patrolling patterns” and with three boats, that’s not possible.

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Peter Shaw

I don’t know who writes the manifestos of Labour, Lib Dems and SNP on defence…you would get more sense from words that you can read in public toilets.

Mark B

Very few people know or want to know much about defence. The Lib-Dems have distanced themselves from the crazy Labour party and are trying to take a pragmatic centre ground position and say they will save money. Swinson sounded sensible to me with the principle if not the detail on defence although nieve on almost every other issue…

Steve H

Liberals and Lefties are the enemy of the Armed Forces……100%.


Honestly Peter, I’d add the Tories to the list. Feel free to check out their manifesto and costings sheets, don’t just take my word for it. Veterans’ affairs and defence get a grand total of 11 bulleted action points between them, tucked away on pages 52 and 53 (out of 63). There’s a whole lot of wording about focussing on x and adapting to threats from y and standing against z. None of it really amounts to anything that isn’t already recognised and part of government policy. They promise to increase the defence budget by 0.5% above inflation every year… Read more »


Indeed the Tories talk strong defence while as in many things disguise cut backs with subterfuge and misrepresentation. Sadly in terms of defence they are probably the least bad option however. On another, though relevent note just listened to the (very brave) author of the book ‘From Russia with Blood’. Would love to hear Sturgeons or Corbyn’s no doubt dismissive and crass reactions to the very scary revelations in that book. Nothing, at least that the more informed, didn’t know of, but the brutal strategies and shear immoral depth and opportunist exploitation by Putin and cronies and the complicitous facilitation… Read more »


I don’t know a lot about the situation, but even from the publicly available information it would be foolish to consider Russia truly friendly to the UK. I’ll check out the book, thank you for the recommendation. Interestingly, something that the SNP and Labour ignore is that Russia and the US are considering bringing back smaller yield nuclear missiles. This is not a triumphant step towards denuclearisation; it has been Russia’s officially stated threat (I’m pretty sure it was from the mouth of Putin no less) that they would escalate to nuclear in the event of a conventional conflict. Smaller… Read more »




why did you miss out the tory manifesto, they’re all as bad/unrealistic/fantasy as the next one.

Steve H

Probably the same wet weekend limp wristed liberal fart bubble …….. The political parties that you mentioned are seriously dangerous for our Country, all of their leaders are no friend of our fantastic, precious Armed Forces….at all.!!!

Daniele Mandelli

Cobblers from the Lib Dems.

You’d need to build an underground base in the Coulport Hills with a submerged entrance, to avoid other nations just looking with satellites and other means to see our 3 boats are sitting in port.

This is done already to a very minor extent in that the Coulport Explosive Handling Jetty is a secure facility, where prying eyes cannot see just how many Trident are loaded aboard inside the structure.

Far different to hiding the Vanguards.


With Scotland wanting a “once in a generation referendum” on an annual basis I wouldnt invest any money in scotland until the SNP are finished or diminished. At some point in the next decade we may find ourselves having to resite the deterrent at Portland or somewhere, a gigantic cost


the last independence vote cost the taxpayer 80 million, if they want another, they should pay for it


“There’s boats in them there hills!”

Very James Bond, Daniele. But joking aside, once again we can observe a level of incompetence from the party. It’s bad for the nuclear deterrent, bad for Faslane and will almost certainly represent a ‘betrayal!’ for Barrow.

The deterrent doesn’t work if your satellites see three submarines alongside in UK waters, or even two alongside and one in refit in Devonport. That’s also where this falls down – if the refit of one takes longer than expected, you’re putting more pressure -literally- on the other two. Case in point at the moment: HMS Vanguard.

Harry Bulpit

Even if we did build these facilities to protect from satellite view, all anyone needs to do is get someone working in one of the local primary schools and let some of the pad brats let slip to their favourite dinner lady that their dad is going away. Then you know.

Bloke down the pub

The biggest ‘cost’ for the Trident system is that after all the money has been spent, you hope and pray that it’ll never be used in anger. This compares with most other systems operated by the armed forces that have a track record of operational effectiveness. To get more value for money from the subs, it’d seem sensible to make them adaptable for launching vl cruise missiles. There are limitations I know from this dual-use but the benefits could take some of the pressure of the Trident budget.

Daniele Mandelli

Are these Cruise Missiles nuclear or conventional? Nuclear cruise can be shot down, and will cost lots of money on top of other purchases. If they are conventional then that is a big no no for me as the “Bomber” ( I’m cured Lusty ) reveals its position in launching them. Where’s the whole idea of the deterrent is that it cannot be targeted in a first strike, it loses itself in the ocean at 2 knots or whatever and is silent and undetectable. And as only 1 is usually on patrol, the RN would need a second boat for… Read more »

Gavin Gordon

The manifesto does not itself refer to a post cold war period, but that was certainly their main point until relatively recently. In spite of that, they are still propounding the same formula today. Regretably, we are firmly back in a cold war scenario where Russia is concerned, together with a relationship virtually indistinguishable from that with the Chinese. In fact, strategically, these two are to a major extent no longer separate defence entities. No problem with the LD continuing to promote mutual nuclear disarmament, a lovely concept, but they do need to finally row back on declaring 3 as… Read more »


What I find quite interesting is that they would continue with trident renawal at all. After all that flapping in Parliament that we should scrap our nuclear deterant, just shows that even the Liberal Dems know that we still need to maintain this capability.

Andy P

3 bombers could work in the short term but as the platforms age they require more maintenance and at this end of the V boat cycle we’re struggling with 4 to keep things going.

In our Defence strategy of death by a thousand cuts, I can see the next step being the end of CASD to save cash. The next stage would be to go to a cheaper option (nuke TLAM or other simpler systems). If we’re serious about a single viable nuclear deterrent then CASD is probably the best option.


But what about DBTE? And surely UMBN is more efficient.

Andy P

Got to be honest Trevor, I’ve no idea what these are and a quick look round google doesn’t help.

I’ll take your word for it though.

Daniele Mandelli

Micky taking on Andy’s acronyms?

I don’t know what they are either.


Alphabet soup !!

Andy P

Trevor, you could always just ask if you don’t know, there’s no shame in it.
CASD = Continual At Sea Deterrent
TLAM = Tactical Land Attack Missile (also known as Tomahawk)

I’ve not made them up to look clever, they’re both terms in reasonably common usage. Just because you weren’t aware of them doesn’t make them “Alphabet soup”.


All very true, but I’m afraid this stuff is getting worse.

Andy P

Yup, you’ve got to hate acronyms in the RN. 😉


🙂 TLAs are the worst…


acronyms should be banned on here i’m fed up of having to look things up!!!!


According to the leader of the SNP in Parliament, the deterrent is no longer worth it as it can be identified by enemy forces and tracked. Obviously, because of this, it should go.

Either he knows something we don’t and he’s just broken the OSA, or he’s lying. Heard him say it on the radio the other morning.

Paul T

Paul – Id be surprised if that is the case – if it was it would make the CASD pretty much worthless,but of course there are exceptions




I certainly hope that even with 4 boats they operate “unpredictable and irregular patrolling patterns”. Or does having 4 boats mean that you have to notify your enemies of where you’re patrolling?

Daniele Mandelli

No. It means one is always out there somewhere ready to retaliate.
That, is CASD.


This isn’t really fact checking, its reinforcing the existing message without really proving the message is wrong. I am not saying the statement is right or wrong, I am just saying it is not fact checking. The factfulness (is that a word) of the statement really depends on our ability to keep secret when the boats are in maintenance or not. If we are able to keep this secret, then even 1 is a sufficient enough random deterrence, as the whole point of a sub based deterrence is not know if it is out there, and even if it is… Read more »


6? Unless we’ve found an extra 2 boats or the MOD has been lying to us all this time, only 4 boats make up the CASD – and one of those is currently in Devonport.

Andy P

Steve, if you want to know what Bombers are where (broadly speaking) as a Helensburgh taxi driver. They certainly know what ones are alongside.


I was actually a proponent of dropping to 3 bombers, being an avid subscriber to the ‘rule of threes’. However, I now consider myself educated on the need for a fourth, effectively a contingency for the normal application of said rule.

Steve Taylor

If anything we need 5 boats not 4.

Cobblers to the Limp Dumbs,

Steve H

Utter crap from the un-Liberal un-Democrats, this pie in the sky, limp wristed liberal nonsense is a serious danger to our Armed Forces and an even larger threat to our National security.
By reducing the number of Dreadnoughts to 3, it leaves us short and would put the fleet and it’s bases in jeopardy. By having 4, there’s always one hiding around somewhere with our nuclear deterrent, this let’s potential adversaries know that we always have that toy in the box if needed.


Trident replacement is very expensive, on a limited budget it is crippling our conventional forces. You can see the merit in not replacing it like for like, either by fewer ssbns, or by cruise missiles and free fall bombs dropped by F35As. By having such weak conventional forces, insufficient asw assets (T26, Merlin HM2, SSKs, SSN, Possidons rtc) our ability to protect ssbns is limited. No layered UK air defence ( just a hand full of Typhoons concentrated on 2airbases). In the real world of just 2% on defence, the like for like repacement of the Trident system and the… Read more »


this worries me

Daniele Mandelli

Andy. One – It’s the Guardian. Two – That article is from 2012!!!

The Guardian once argued for no armed forces AT ALL so they will be all over problems with the military and emphasise any issues I feel.

David Flandry

They will be serving vodka martinis, shaken not stirred, in hell before Russia or China agree to armament limitations.