Much has been made this week of three of the Royal Navy’s four Vanguard-class ballistic missile submarines being at sea at the same time. Depending on what you read, it was a signal to Moscow, a heightened alert or a sign that something had gone wrong. It was none of these. It was a programming matter, plain and simple. Not messaging, not deterrent effect and definitely not escalation.

To keep one complex warship permanently on task you need just over three: one on operations, one working up, one in maintenance or on leave. “Bombers”, as the nuclear missile subs are known in the Navy, are so complex, and the requirement to keep one armed and ready out on patrol is so absolute, that one in four has become the accepted minimum, and even here we have been cutting it fine of late.

The cycle is also fluid: sometimes there is just one boat at sea. More often recently we have had one on patrol, and then one on trials and two alongside (often in deep maintenance) and so on. The people who work this schedule out will be doing it with a fine degree of granularity based on maintenance schedules and then adjusted due to emerging defects and this will be done months, if not years, in advance. I guarantee you it is not rearranged to send a message.

That it is noteworthy just now, however, tells you how poor bomber availability has been recently. Every one of the last nine completed patrols has run over five months. Almost unimaginable 204-day and 205-day patrols have now happened – the sort of record you don’t want to be setting and one the boat currently on patrol may still break. In the 90s, when the ageing Resolution-class boats were running beyond their design life because the Vanguard boats were also late, their record patrol was 108 days. I remember people at the time saying we must never allow this to happen again, the strain on the ship’s company is too much. And here we are again, almost twice as bad.

None of this was an accident. When the 2006 White Paper committed Britain to replacing Trident, the first new submarine was due in service in 2024. In 2010 the Cameron government deferred the main investment decision to 2016, which pushed that date back to 2028. Since then it has slipped again. The MoD now says only “early 2030s”, which many believe means 2032, 16 years after first steel was cut in 2016. Add decades of under-investment in docks and support (HMS Victorious has been in deep maintenance at Devonport since May 2023), and for much of this year only two of the four boats were in the rotation.

As if to demonstrate we don’t confine this delay malaise to just submarines, the defence investment plan in June announced a “Common Combat Vessel” to replace the Type 45 destroyers from the early 2030s. Four months on, nothing. Type 26 and Type 31 have both been slowed, the MoD now won’t give an in-service date for the latter, and the Norwegians, who are buying Type 26s, are getting frustrated. We don’t learn.

Back to the three bombers: was there deliberate messaging? No, or the system would have got ahead of the story. As ever, “we don’t comment on submarine operations” has left the field free for everyone else to do so, often inaccurately. That doesn’t mean there isn’t implicit messaging which in this case is good news: our deterrent availability is improving. When this might carry over into shorter patrol lengths is the key question for the men and women in that rotation.

“De-lousing” is a term that has been bandied about a lot lately as well, intended to mean operations by attack submarines intended to make sure that a bomber heading out on patrol doesn’t pick up a Russian shadower. This is not what de-lousing actually is, in a submarine context. There is a procedure of that name: it is highly classified when it does occur, and it is very rarely done. In reality, the very last thing a bomber wants is another submarine anywhere near it. When it has to happen, it is done by one of our own SSNs and the records are about as classified as it gets.

We absolutely would not use another country for it, another rumour circulating recently. Using French and US submarines for wider anti-submarine work in the North Atlantic is something else entirely, and in light of our woeful SSN availability in recent times, both inevitable and unfortunate, but that is not de-lousing.

Nor is one of the two bombers not on patrol being used either for this or more generally as stand-in SSNs. This occasionally gets discussed until it reaches the part of the submarine community who understand the risk inherent in using a strategic asset in a role that increases the chance of counter-detection, who then dismiss it out of hand.

For those who think the deterrent should be scrapped, it was established long ago that the British electorate does not agree with you – and the savings would be tiny, in government terms. My own view is that it would be a fine thing to live in a world where these weapons were not required to deter inimical regimes, and perhaps one day we will – though there are those who’d argue that we would be well advised to still retain a few nukes for purposes of asteroid defence.

In any event, we do not live in such a world. While that remains the case, delivery by submarine removes the incentive for a pre-emptive strike: it is very easy to argue that it is nuclear missile submarines, as opposed to other types of nuke, that have prevented nuclear war.

Three bombers at sea, then, are not a signal, a crisis or a provocation. It is the programme working, and better than it has done for a while. The task now is to keep it that way, improve the deterrent effect and for the sake of the crew’s sanity get the patrol lengths down.