Britain has been promoting this because they were unable to deal with Russia and in fact, had many double agents in the 70s and 80s who were recruited by the Kremlin.
Americas folly, was listening the the Brits advise them on intel and convince them that Russia is a greater threat than China. I have a feeling the Americans understand now how absurd this opinion was, and thus, they are now scrambling to play catch up on Taiwan and the SCS and Asian influence.
Russia is definitely making moves on global soft power, just as China is. Russia is now telling other Western allied nations "look at the West and what their priorities are, do they align with your priorities? Do they seem like they represent the future of the globe? Would you want them to?"
They recently delivered a number of missiles to India. Probably angering China, but definitely building greater rapport with India and trying to split up the Quad. I read many Indian posters say "better to not take sides and just put our interests first, deal with Russia and America as need be". This is problematic for the West, and we had better not get complacent.
As usual, once the Quad Bloc was set-up between America, Japan, India and Australia, the U.K tries to nudge their way in and publicly announcing they may too join the Quad. "Huh"? Who publicly invited you? This further complicated the already new and fragile relationship (there is more to this Bloc as well, involving S Korea. Moon is at he helm and he is currently soft on China).
Maybe the Brits should improve their intel capabilities and get out of the nepotistic, monarchal manner in which they recruit. They had better find patriotic, honest and sober Brits to give analysis not political patsies who never earned a position in their lives (hey, that's the Canadian Way too. Imagine that?). It's the political game injected into the intel that ensures failure.
Russia isn't the Big Dog in 2021. Yes, they pose a threat, they are far from the only nation and they've received far too much credit vs other adversaries.
The problem is that China has bent the rules and gotten away with it so frequently that now Russia feels emboldened as well. "Hey, China can fly their jets to the Taiwanese line without consequences? Send "fishing vessels" by the hundreds into the Philippines and not be arrested? They can build islands in the SCS, steal from the U.S, publicly threaten them and there are no consequences? Ok, sign me up for some of this stuff, fire up the subs boys, let's go rattle the Brits after a few shots of vodka".
This is all on the feckless West. Leadership in the U.S used to be made up of former soldiers, real hardened men who loved their country and didn't take shyte from Commies. The Russians (China today) respected those men as they knew they meant business and wouldn't mess around in the face of potential threats.
Now many Western nations are made up of activists, high school drop outs, bartenders and in many cases, self serving people who don't even like their home countries nor their constituents.
You tell me what you would do when facing this "opposition" if you were Russia or China? If the West doesn't start playing for keeps and confront growing threats, the threat will be at their doorstep.
If the Brits feel threatened by these subs, than advise the Russians, very publicly if you must, that there will be consequences. Starting with economic, followed by a warning shot, followed by a direct hit by any sub that enters their waters.