England's Jos Buttler has apologised for over-stepping the mark with his verbal attack on Vernon Philander and plans to save his aggression for when he has bat in hand.

The wicketkeeper allowed his mood to boil over during the dramatic fifth day victory in Cape Town, serving up an expletive-laden outburst after Philander declined to get out the way of an incoming throw.

His blunt description of the Proteas seamer, as well as a colourful reference to his waistline, was not designed for a family audience but was broadcast via the stump microphones and soon shared far and wide on social media.

Buttler was fined 15% of his match fee and handed one demerit point by the match referee and accepts he fell short of the standards required.

"I fully understand that as role models we have a duty to behave in a certain way. I'd like to apologise. That's not the way to behave," he said.

"I'll take the slap on the wrists and I understand that as role models you can't get away with using language like that. I'll wash my mouth out with soap!

"It was one of those moments, I lost my head for 20 seconds. If I see Vernon I'll say I'm sorry."

Buttler suggested most players would prefer the audio levels to be turned down between deliveries, allowing some leeway for private exchanges in the heat of battle.

"The stump mics have been a bit of a debate for a while now, whether they should be up all the time, on and off, or off completely," he said.

"I think as players we'd probably like it to be off and then what goes on the field can stay on the field. But that shouldn't mean things can get out of hand. For viewers at home it probably adds a lot to the experience, so it's a tough one."

While Buttler is likely to be minding his manners when the third Test gets under way in Port Elizabeth on Thursday, any courteousness will not extend to his batting.

He was dismissed for 29 and 23 at Newlands but in both innings showed signs of the free-flowing strokeplay that he often keeps back for limited-overs cricket. Three times he cleared the ropes, hinting at a shift in mindset from a player who has occasionally seemed shackled in his England whites.

"I do think I can get more out of myself by trying to be positive and counter-attack," he said.

"It's certainly something I will look to try and continue if the situations allow, to try and throw a few punches back, to try to make the most of my talent and the skills I've got. I'll just try to be authentic and play my way."

England trained at St George's Park without captain Joe Root, who was kept back at the team hotel with an upset stomach. There are no serious concerns about his condition but, having seen 11 players and six backroom staff fall ill during a chaotic start to the series, all precautions are being taken.

More concerning, perhaps, was Jofra Archer's performance in the nets. With James Anderson having flown home, England would love to have a fully fit Archer ready for recall.

But the right elbow injury which ruled him out of the previous Test is still causing problems and he was only able to perform at around 80% capacity. If the 24-year-old is to push for selection, he will need to up his workload on Monday.

Mark Wood, the only other express pace option in the squad, has declared himself ready for selection and bowled at full tilt in training but also represents something of a gamble having not played since the World Cup final in July.

Should England choose to play it safe and hold the quicks back for the decider in Johannesburg, then Chris Woakes could find himself back in the XI.

"There's some good guys on the sidelines, aren't there?" said Buttler.

"It's exciting for those guys to know there's an opportunity going into this game. They will be charging in at the nets and trying to make that place their own."