Postpublished at 17:20 British Summer Time 27 June 2022
It'll be Lauren Bell with the new ball from the other end.
Bell, who is one of four debutants for England today, trapped Lizelle Lee lbw for her first Test wicket earlier.
Kapp makes superb 150 from 45-4
Kapp's first century for South Africa
Falls to stunning Beaumont catch
Bosch 30, Luus 27
Cross 4-63, debutant Bell 2-47
One-off Test, day one, Taunton
Ffion Wynne and Callum Matthews
It'll be Lauren Bell with the new ball from the other end.
Bell, who is one of four debutants for England today, trapped Lizelle Lee lbw for her first Test wicket earlier.
Alex Hartley
Former England bowler on BBC Test Match Special
I think another 20 runs or so and it's South Africa's day. England have been brilliant with regular wickets but Kapp has been exceptional. They only thing is that Kapp has to open the bowling having been out there batting all day and that's a tough one.
Marizanne Kapp works a single into the leg side and that leaves Tumi Sekhukhune with two balls left to face.
Issy Wong offers her a freebie, with the ball straying down the legside and the South African number 10 just helps it round the corner, off the glove, for four. It was fairly sloppy keeping from Amy Jones too, to be fair.
Sekhukhune looks handy enough with the ball. She does well to jar her bat down and keep out a good yorker from Wong.
Time for a drink. It's a beautiful sunny evening in Taunton.
Alex Hartley
Former England bowler on BBC Test Match Special
What a great start from Issy Wong with this new ball. Perfect seam delivery and squares Kapp up.
Offft! Beauty from Issy Wong to start.
She square Marizanne Kapp up and beats the outside edge of the South Africa all-rounder.
The moment draws excitement from the England fielders. They'll want to be batting shortly.
Thank you, Ffion.
It'll be Issy Wong with the new ball. We could see some pace here.
And with a change of ball brings a change of live-texter.
I'll hand you back to Callum Matthews for the rest of the session.
Georgia Elwiss
England all-rounder on BBC Test Match Special
You would think that Lauren Bell will take the new ball. Nat Sciver isn't shy of a new ball but they might go for Issy Wong.
There are options for Knight.
Ecclestone strays onto Kapp's pads and she whips it away for four valuable runs and brings up South Africa's 250 in the process. I'm sure they'll have wanted more but this has been a brilliant recovery from 89-5.
The new ball is now available for England. If Lauren Bell and Issy Wong can find the same amount of swing as they did this morning, it will not be straightforward for South Africa.
Henry Moeran
BBC Test Match Special
It's a lovely day in the South West...I'm thinking about an ice cream.
Hartley's keen.
Brutal but brilliant there from Katherine Brunt, which I think describes her pretty well in general, to be honest.
Kapp takes a single from the fifth ball and leaves Sekhukhune with just the one to negotiate, which she does. A slow-scoring couple of overs for South Africa but as long as Kapp is still there, they won't mind.
Henry Moeran
BBC Test Match Special
There's a rowdy person in salmon pink who shouted at Nat Sciver on a misfield: "I'm going to divorce you."
It can only be one person and she's making a right old racket....yes, it's Katherine Brunt!
Close! Sekhukhune has two balls to block from Sophie Ecclestone to keep Kapp on strike for the next over and the first of them just evades a diving Tammy Beaumont at short leg.
The next is defended much more solidly - job done.
Georgia Elwiss
England all-rounder on BBC Test Match Special
I think the next few overs are really telling over whose day it has been. If South Africa can get to 280 plus they'll be really happy after that start. England will want to keep them to 260 max but it will be a tricky time to bat tonight if England do come in.
South Africa will be pretty pleased with what they've done here and a lot of that goes down to Kapp and this performance. All these runs are so valuable.
Sekhukhune drives the ball firmly from the first ball to get Kapp back on strike.
Kapp then drills one to long-on but turns down the single - and rightly so, as she hammers the next ball straight back over Lamb's head for four!
She then nabs a single from the final ball to keep the strike. Expertly done.
Emma Lamb is into the attack for the first time with her off-spin.
She's bowled brilliantly for Thunder in the domestic game this year - can she become the fourth player to pick up a wicket on debut today?
Kapp must have a bad back from carrying this innings for so long.
She elegantly opens the face of the bat to deftly guide the ball to third man for four before getting down on one knee and slogging Ecclestone over mid-wicket for another.
She can do it all.
Georgia Elwiss
England all-rounder on BBC Test Match Special
South Africa would be in a deep hole without Kapp. She's shown what a fantastic player she is and some of those cover drives have just been tremendous.
New batter Tumi Sekhukhune safely blocks her first three balls. She has a pretty simple job here - just don't get out.
Marizanne Kapp just needs someone to stay with her.
Emily Windsor
Southern Vipers batter on BBC Test Match Special
You feel like now could be the time we see Kapp play more shots. She's going to keep the majority of the strike and could really look to accelerate with the lower order.