Today I'd like to continue the theme I've been harping on recently about UK defence in the context of just pure defence, i.e. protecting the UK, without any concern for foreign adventures and UN missions etc. Putin is the new black these days and everyone seems to think the UK should suddenly be re-arming ready for world war three because... Russia. So an interesting topic at such times would be - I think at least - the issue of conventionally powered submarines.
The UK's last foray into this world ended with the Upholder-class diesel powered subs, which served for a grand total of four years in the early nineties before being decommissioned and sold off as part of the "peace dividend" (the dividend that just keeps giving....). Since then it's been all nuclear for the UK, in ever decreasing numbers which in the case of the Astute-class seems likely to come to rest at seven. Meanwhile the rest of the world has somewhat embraced the concept of the conventional submarine due to the lower construction and running costs, accepting a trade off in many performance measures vs a nuclear submarine in exchange for the ability to at least play in the game, and understanding that even conventional submarines represent a formidable foe for surface vessels when properly handled. Stories abound about European operated conventional subs sinking entire US carrier battle groups on exercises. Even if the exact details of each of these incident might tell a different story to the one that appears in the various press releases, it would be foolish to assume that despite quite a lot smoke there is absolutely no question of there being fire.
The UK reluctance to invest in such a capability has its own merits. Question one; where would you build them? Barrow is tied up building the Astutes and planning for the successor class to the Vanguard SSBNs. Question two; what would the UK do with them? Nuclear powered attack submarines (SSN) have been the favourite for a while now due in large part to their exceptional range and speed. They are Fisher's dreadnoughts for the 21st century. Endurance and speed that a conventional submarine can't hope to match.
Well, as the Russian bear rising seems to be the flavour of the month right now then actually the conventional sub seems to make a lot of sense. From the Royal Navy's perspective the biggest concern in relation to the Russian Navy in some hypothetical future war is probably the dual threat of Russian submarines and surface groups penetrating into the Atlantic and disrupting supply lines with the US, while also threatening the UK deterrent. To do this the Russians would have to make their way through the Greenland-Iceland-UK gap. Now in days of yore the UK used to be able to help protect this gap with its maritime patrol aircraft but whoops, budget crisis, MPA no more. But protecting and patrolling this gap - and indeed the surrounding UK waters - is right up the street of a conventional sub (Henceforth SSK, to save me having to keep typing "conventional sub").
The mission plays perfectly to the strengths of the SSK as a slow but virtually silent ambush predator. Whispering back and forth through local areas of interest to the UK, the SSK would provide a powerful tool in the Royal Navy's underwater arsenal, while the SSNs roared about the open oceans. As far as purchasing some of these goes, a UK new build, homegrown design would obviously offer tailor made advantages as well as being a potential source of exports given the current popularity of these kind of subs, but a foreign buy would be more likely. Given the low(er) cost of SSKs in comparison to an SSN it shouldn't break the bank to purchase a few and there is certainly plenty of competition on the market place right now, from the German Type 212, to the French Scorpene and Swedish Gotland-class.
If we're all really serious about this "the Russians are coming" narrative that has developed lately then to me a small fleet of SSKs seems a highly logical choice.