In 2014, 13-year-old Malavath Poorna became the youngest girl to summit Mount Everest. At the same age, 51 years before, Stevie Wonder was the youngest to have a No. 1 in the US charts. Even though we occasionally get the likes of Stephen Cook, who became the fourth-oldest debutant to score a century on day one in Centurion, we live in a world of wonder kids.

Three days after his 17th birthday, when Quinton de Kock made his first-class debut, he looked like he would be one of them. Six days before his 21st birthday, when he stuck his third successive century against India in ODIs, he was one of them. But now, just over a month into his 24th year, de Kock is no longer a wonder kid. He has grown up.

South Africa needed him to when they slipped from 237 for 1 to 273 for 5 during Friday's final session. The four wickets that fell for 36 runs were not just any four, they were the batting core. Hashim Amla, AB de Villiers, Stephen Cook and JP Duminy left the last recognised batting pair, Temba Bavuma and de Kock, to face the second new ball.

The elder statesmen may have passed on advice about being circumspect, buying time or batting sensibly; de Kock did not seem to have heard. Six overs into the new nut, he took on the England spearhead, James Anderson, first on the front foot with a crisp drive, then twice on the back foot with a punch and a pull. In the next over, Bavuma attacked Stuart Broad and by the close the pair had put on 56. If that was a glimpse into South Africa's long-term future, it may not look as bleak as it has sometimes seemed over this series.

South Africa's more immediate concern was this morning when de Kock threw his bat at a wide delivery from Anderson and with that, almost threw it all away. It was fitting that it was Ben Stokes, the man stationed at gully, who could not hold on. Stokes would have understood that shot perfectly. It's a shot he would have played.

Batsmen like Stokes and de Kock don't mind taking risks. "It's just the way they play," is the rhetoric which unburdens them of responsibility. Today, de Kock could not escape that duty.

Shortly after his reprieve, he lost both Bavuma and Kagiso Rabada. He was left with the tail but he did not seem to be preparing for a speedy end. Even though he slayed width from Stuart Broad, he also stole as much of the strike as he could. In the first 14 balls of his partnership with Kyle Abbott, de Kock faced nine.

Once Abbott was a little more comfortable, the ball was a little older and the bowlers a little more frustrated, de Kock settled into a more relaxed role. When Dane Piedt replaced Abbott in holding up the other end, he responded by turning aggressor once more. The part Piedt played cannot be underestimated. He batted for almost two hours and faced 104 balls for just 19 runs. He gave de Kock the freedom to press the advantage home.

De Kock's first fifty came off 68 balls, his next fifty off just 36. He scored equally all around the wicket and targeted the least-experienced member of England's attack, Chris Woakes, who was unlucky not to have the last laugh. When de Kock was on 80, Woakes drew the edge but the ball flew between between Jonny Bairstow and Alastair Cook at slip.

De Kock's innings was a testament to the development he has made over the last three years, a progression which has gone unnoticed

The most impressive aspect about de Kock's assertion of authority was the way he played spin. He took 45 runs off the 28 balls he faced from Moeen Ali, who also could have taken revenge when de Kock drove to short cover but Cook spilled it. De Kock was on 90 at the time; four balls later, he had his first Test hundred.

The value of that innings was obvious from de Kock's reaction - the air punch, the whirl of the bat, the leap - but it worth more than the numbers. It was a testament to the development de Kock has made over the last three years, a progression which has gone unnoticed against the backdrop of his limited-overs' returns.

De Kock has been grafting in the longest format since his first match for Gauteng in 2009. He scored 9 and 6 but did more behind the stumps with five catches and a stumping. The next summer, de Kock was properly part of the province's plans. In the first four games he played in the 2010-11 season, he was deployed everywhere from No. 7 to the opening berth and scored a century and two fifties. That earned him a promotion to the franchise side, the Lions, where he found the going tough; his top score was 35 and he did not keep.

When the next season began he had to start again in the provincial set-up. In five games for Gauteng in 2011-12, de Kock struck two centuries and three fifties and got another chance in the franchise team. He was more successful, albeit with the added job of keeping wicket. In the second match that summer, de Kock scored 194 opening the batting in the second innings for the Lions, who were following on. He did not save the game but he did come to the attention of the national selectors.

He then made his T20 international debut in late 2012 against New Zealand. But even there, de Kock's first showings at that level did not stand out. He struggled in Sri Lanka and was sent back to the domestic game to tighten up his technique. When he returned against Pakistan, he scored his first ODI century, which was his establishment innings in the shorter formats.

His Test career has followed a similar path. After debuting when Alviro Petersen fell ill the night before the second Test against Australia in February 2014, de Kock was given a permanent spot when South Africa toured Sri Lanka and Zimbabwe that year and put in promising performances before hitting a slump.

He was dropped 12 months later, in Bangladesh, after a lean patch that had stretched from the World Cup. He was demoted to the South Africa A side, where he scored a century against India A, but was not picked for the Tests in India, even though he was back in the runs. A half-century for South Africa A against England ahead of this series was still not enough. Only when de Villiers complained of a heavy workload was de Kock recalled but, on his comeback in Cape Town, he scored 5 and then missed the Wanderers game with a knee injury.

But he got a second second chance at Centurion and he did not let it go. He played with the maturity that puts him past wonder kid status and an innocence that keeps him in it.

At the end of the day, a day in which de Kock spent every minute on the field, he was first to reach the boundary rope to leave it. But he didn't know if he should step ahead of his seniors. So he turned back to de Villiers, as though to ask. De Villiers gestured that he should lead them off. The crowd cheered. The wonder kid was wonderful again.

Firdose Moonda is ESPNcricinfo's South Africa correspondent