'Jonny was tested in certain areas but he has worked on it. He handled it brilliantly'

England's Ian Bell acknowledges the crowd's applause after reaching his fifty at Lord’s yesterday (AP)

Jonny Bairstow could be forgiven for having the image of Kemar Roach uppermost in his mind as he walked to the wicket yesterday for perhaps the most important innings of his nascent England career.

Bairstow struggled against Roach's short deliveries in his first two Tests, against West Indies earlier this summer. Here the South African close fielders were quick to remind England's young No 6 of those difficulties, mentioning Roach's name several times as Bairstow tried to establish himself at the crease.

As if that were not enough, Bairstow also knew he was in the team only because Kevin Pietersen, England's most high-profile player, had been dropped. This is only Bairstow's fourth Test and judgements are necessarily provisional, but if he can overcome these mental bugbears and score 72 not out against one of the best bowling attacks in the game, we can guess at least that he has a strong backbone. And, of course, this is a Test that England must win to stop South Africa replacing them at the top of the ICC rankings. So, no pressure.

Bairstow and Ian Bell added 124 for the fifth wicket to help England recover from 54 for 4. Bell's dismissal in the final session dented the home side's improving day, but they were quietly satisfied to reach 208 for 5 at stumps, a deficit of 101. If Bairstow had been worried about Roach or Pietersen, Bell said, he had hidden it well.

"I don't think he would've thought about it," Bell said. "When the squad got together, winning this Test was the only thing on our minds. If we had been thinking about other issues, Jonny would've been under a lot of pressure, but he was just himself and that seems to have worked really well.

"He was tested in certain areas, but he has worked on those and he handled himself brilliantly. He has to do it again today but what he has done already is fantastic.

"He didn't try anything different and he didn't change anything as he got further into the innings. He scored a century for England Lions against Australia A, so he came here in pretty good nick and with great confidence."

Bairstow eschewed the chest guard during his last Test appearance at Lord's, against West Indies in May, but he was more cautious here and looked more confident with the extra protection.

Morne Morkel and Dale Steyn are two of the most fearsome fast bowlers in the game, but Bairstow handled their threat with confidence and maturity. "Against West Indies, maybe Jonny didn't know whether he wanted to take on the short ball or get under it," Bell wondered. "Here, he committed to doing one thing or the other.

"When he wanted to avoid it, he showed good technique to get his hands out of the way against Morkel and Steyn, and when he wanted to take it on, he made sure he committed to it."

This morning Bairstow and Prior will have eight overs to negotiate before the second new ball is taken. England will need their lower order to do a similar job to that of South Africa's, who put on 146 for their final four wickets.

"It will be an action morning," Bell added. "With Prior, Bairstow, Stuart Broad and Graeme Swann to bat, there won't be much blocking around."

Bell played patiently for 58 before he was tempted into a loose stroke by Vernon Philander, who took 1 for 30 to add to the 61 he completed in the morning. He was impressed by Bairstow, and said: "We saw the footage of what happened against West Indies, but he played very well. [England] have quite a long tail, so things are playing into our hands."