At the start of the third day's play, there was an intriguing chat on commentary between Matt Prior and Kevin Pietersen - yes, TalkSPORT has bought the pair together; they'll be pairing Ian Botham and Ian Chappell next - over the future of conventional off-spinners in Test cricket.

The conclusion, to paraphrase only a little, was they are an endangered breed. But, unlike the rhinoceros, Pietersen didn't seem especially concerned with their preservation. Again, to paraphrase only a little, both he and Prior felt that, in the modern game, any off-spinner without some mystery or at least the ability to challenge both edges of the bat was likely to struggle.

But here, for the second Test in succession, Dom Bess supplied the case for the defence. Having admirably performed a holding role in Cape Town, he showed he could also perform a more attacking role here. Taking advantage of a dry surface, he showed the conventional skills - most of all control, but also subtle changes of angle and pace - still had a place in the modern game. Already he has become the first England spinner since Derek Underwood, in 1975, to claim the first five wickets in a Test innings and the third-youngest England spinner (after Pat Pocock and Underwood) to claim a five-for in Test history. If the rain relents, there is a good chance there will be more to come.

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It's true, Bess does not possess the eye-catching skills of Rashid Khan, Sunil Narine or Saqlain Mushtaq. He cannot turn the ball both ways. There is no doosra. Analysts will not be glued to their screens working out how makes the ball fizz and dip and, the cynics have suggested, he could only take wickets on the helpful surfaces of Taunton where, until today, six of his eight five-wicket hauls in first-class cricket had come. Only a few months ago, he was unable to get into the Somerset team and went on loan to Yorkshire.

But what he can do, at this stage of his career, is maintain his line and length. He has conceded only seven boundaries - and an average of 1.64 runs per over - in his 31 overs to date. As a result, he has kept the batsmen under pressure. And what he can do, at this stage of his career, is apply a series of small variations to lure batsmen into errors and take advantage of helpful surfaces.

The wicket of Faf du Plessis provided a fine example of this. The South Africa captain had just driven him for a couple of fours. Bess responded by dropping his arm a little lower, gaining just a little drift away from the batsman to draw him into a forward prod, only to turn the ball sharply off the pitch and take the inside edge. Ollie Pope, who looks terrific at short-leg, did the rest. Any off-spinner would have been happy with that.

There were other moments which showcased those subtle skills. By changing the seam position - including bowling with a scrambled seam - he manages to gain variation from some balls skidding on and others gripping and turning. Dean Elgar, who was probably the one man in the top five to play Mark Wood with any confidence, was defeated by just such a delivery: coming forward to one he expected to turn, he was slightly late as the ball skidded through a little quicker, taking his inside edge before ballooning off his pad to short-leg. Again, that's fine bowling.

The ECB deserve some credit for Bess' development. At the end of the season, they and Somerset agreed he should be given an extended break to clear his head after a sometimes frustrating few months. As he has previously said, he "lost a lot of confidence within my game" after "falling off the [England] radar a bit" after his brief spell in the England side in 2018.

Having allowed him that time, they identified the ideal coaches or mentors he could learn from - they were after spinners who relied on subtle variations rather than extravagant natural ability - and invited him on a spin bowling camp in Mumbai. Those coaches were Rangana Herath, the Sri Lanka left-arm spinner, and Richard Dawson, who played seven Tests for England as an off-spinner in the early years of this century.

These were wise choices. Herath, in particular, enjoyed an outstanding career as a traditional spinner. And somewhere along the way, Bess has learned that by concentrating on building pressure and by embracing those little variations, he gives himself the best chance of success. In these two Tests, he has looked a better bowler than he did when the Championship season finished in September. He also credited Jeetan Patel, who is with England as a spin bowling consultant, for his advice in helping him gain more bounce and pace.

"That ball to Faf was something I'd been working on with Herath," Bass said. "I started around the wicket and he came at me quite a lot, so I tried to change the angle. I dropped my arm a little and it bit off the surface. It's really nice to work on something and see it work.

"Then with Elgar - who I played with at Somerset - I wanted to make sure I was always challenging him. I looked to go a little under the ball and luckily it kicked on a bit. Some spun and some didn't and Ollie Pope held a great catch.

"I'll cherish this for a long time because I've worked very hard for days like this. Technically I'm getting a lot stronger through repetition. There's still a lot of work to do but hopefully there's a lot more to come."

But before giving the ECB too much praise for their wisdom, it should be acknowledged that Bess was not in the original tour party. And as time goes on the selection of Matt Parkinson, who played four Championship games for Lancashire in 2019, looks ever more odd. It must have been painful to see an injury replacement - called up for the ill Jack Leach - who had not enjoyed the benefit of any warm-up games come into the side ahead of him, but, suffice to say, at this stage of his career, Parkinson looks far better suited to the white-ball game.

"I'm gutted for Leachy, he's had such a tough time these last six weeks," Bess said. "I know he'll be happy for me. He'll be working really hard to get back for the Sri Lanka tour. I'd love to play together. That would be a really nice touch if we could take wickets together for England as well as Somerset."

Equally, the ECB might do well to reflect on the apparent crackdown on the surfaces at Taunton. It is surely no coincidence that England's two first-choice spin bowling options have been developed on turning pitches - just as they were in Northampton, not so long ago - which provide scope for lots of bowling. Yes, there is a distinction to be made between acceptably turning surfaces and ones which offer variable bounce and excessive assistance. But it is also no coincidence that Bess responded to this relatively helpful surface in a calm and constructive manner; something which had not always been the case with Moeen Ali, for example, who sometimes looked more comfortable when expectations were lower. Not for the first time, the thought occurred that Somerset deserve credit not censure for their spin-friendly pitches

Bess had a couple of other factors in his favour here. The first, as was the case in Cape Town, is that this South Africa side is, generally, oddly passive against spin. Other sides - better sides - will surely look to hit Bess off his length. The other factor is that he was bowling when his side had 499 runs on the board. That makes a huge difference in terms of the fields set, the mentality of the batsmen and the time the fielding captain can stick with plans. It won't always be this straightforward.

But everything suggests Bess has the character to cope with adversity. He has shrugged off being unable to get into his own county team, after all, and being called into this tour party without a competitive game since the end of the English season. He made a half-century on Test debut and followed it with 49 as nightwatchman in his second Test. And he's still just 22. Suddenly Moeen's exile does not seem quite as urgent an issue.