There was drama right at the end when, with 80 minutes played, Australian referee Angus Gardner consulted the television match official to see if fly-half Farrell had committed a no-arm tackle on Springbok replacement Andre Esterhuizen.
Gardner's position though has been strengthened by the fact that Farrell wasn't cited afterwards.
Kobus Wiese (1995 World Cup winner): 'I checked with three current worldwide referees on the Farrell "tackle" and the decision was unanimous - it should have been the easiest yellow card to Farrell'.More news: Trump heads to Georgia, Tennessee with 2 days until midterms
"You can get cited for something you did at a party when you were 15, anything could happen".
After looking at the replay, the officials ruled that Farrell had made enough of an effort to wrap an arm round his opponent to make the tackle legal - leaving the England man punching the air in delight.
Eddie Jones was in a defensive mood when he spoke to the media after England's narrow 12-11 win over the Springboks at Twickenham this afternoon. "That's the big thing for us". Like, I don't understand this, guys. We're a bloody good team. We lost a few games but we played tough today and we won. "Sometimes you can take what you want from it", Farrell said.
"You're going to do it at some stage, you know that".More news: Late Marcus Rashford goal gives Manchester United win at Bournemouth
This was England's first match since Jones had brought former All Blacks coach John Mitchell into his backroom staff as defence supremo.
"When you get in those arm wrestles, someone's got to give".
However, Cain did also say that it would be possible for England to secure an almighty upset, providing the stars align for Jones' side.
The hit was described as a "good solid tackle" by England coach Eddie Jones but appeared to divide opinion in the rugby world, and not just on nationality lines.More news: Mauricio Pochettino wants to take Tottenham Hotspur to ‘last level’
The Saracens ace booted the ball through the middle of the posts from wide on the left with just seven minutes to go, handing England a crucial win ahead of next week's highly-anticipated clash with New Zealand.