So while Aggers talks to his View from the Boundary guest, antiques expert Philip Serrell, let's recap a rather frenetic morning's play...

Henry Blofeld
BBC Test Match Special

It's been really good Test cricket this morning.

And that is lunch. A terrific session of Test match cricket.

Joe Root is quite a talent.

In a moment of rage after a dismissal in the winter I may have said Joe Root was overrated. I apologise, Joe.

He is anything but.

Henry Blofeld
BBC Test Match Special

I've never seen Root bat better than this.

Root reaches brilliant half centurypublished at 17 overs

17 overs

Faf du Plessis has had enough of his second-choice seamers. They've leaked far too many runs. Time for spin.

Give this man a knighthood. Another four to Root off the back foot. That's the England skipper's 50.

Stephan Shemilt
BBC Sport at Trent Bridge

Is Joe Root playing the same game as everyone else? The England openers were completely swamped by the new ball and Gary Ballance looks like he's batting on a frozen lake. Root, meanwhile, draws purrs of appreciation every time he makes sweet contact with the ball.

Root has played this as well. Brilliant stuff. He waits and waits and just guides a defensive shot down to third man through the gap in the slips. It's like he's playing with the field.

Root is two away from a half century and has only faced 38 balls. Outstanding counter-attacking.

As I thought. Root whacked the ball into the pitch.

The England skipper is still there and still hitting fours. This one is a pull. Olivier is not quick enough to trouble him.

This looks like a waste of time. Root has played the ball back to Olivier but the bowler is claiming a catch.

Did Root hit it into his boot? The umpires are going to check. The soft signal is not out.

Graeme Swann
Ex-England spinner on BBC Test Match Special

Joe Root is a batsman who likes to steal the strike so the best option against him is to keep him at the other end, frustrate him and bowl at a slightly awkward Gary Ballance instead.

Henry Blofeld
BBC Test Match Special

Root has played two slightly naughty strokes in the last over or so.

Better from Morris. The South African beats Root's outside edge with the England skipper playing a bit of a waft.

But again that's too straight. Root picks up three.

Here's an example of Root putting away the wayward Morris earlier.

Chris Morris is bowling some rubbish here. Full and wide and Ballance just throws his hands at the ball and picks up four.

Root and Ballance have hit 11 fours in their partnership of 63 in just 61 balls.

Image source, Getty Images

Duanne Olivier is not the most imposing quick bowler as his sprints in, shirt baggy around his slight frame. I think he's going to be very much an outswing bowler with his action but there is no reason that can't be effective as Root plays and misses for the first time.

But South Africa have been just too inconsistent since their good start. Another ball on the pads allows Root to pick up a couple.

Image source, Getty Images

Graeme Swann
Ex-England spinner on BBC Test Match Special

Joe Root times the ball so well, it appears as though it's been clobbered to the boundary.

It is definitely starting to brighten up out there. England will be hoping batting will get easier. Regardless of the swing Ballance and Root are going well and Morris in particular struggling to control the ball. Once again the final ball of the over brings four.

AP‏: Joe Root is so good at coming in during a mini-crisis and always finding a way to completely switch the momentum. World-class.

Jonathan Agnew
BBC cricket correspondent on TMS

My word, Joe Root is playing so well.

Another change from South Africa as Duanne Olivier has his first bowl. This is just his second Test and I must admit it's the first time I have seen him. He's getting it down at around 83mph and is getting plenty of shape away from Root and into left-handed Ballance.

His start to the over is good but the final ball is on Root's pads. Four more. You'll learn not to bowl there, Duanne.

Image source, PA