England find a way to win as the 'easy semi-final' veers drastically off-script

England has a team song - a victory ballad - and part of their inspiration during this tournament has been the desire to sing this secret ditty when they win at Lord's. These are the kinds of made-up team rituals that keep teams together on hard days. But this was not supposed to be tough; this was supposed to be the easy semi-final.

England are clearly a better team than South Africa. For all the incredible improvement that South Africa have made, there is still a fragility to their batting order: they still have a far lower cling when it comes to their top order and they always run themselves out. Batting first against England, they have never scored more than 222, and even when they made over 300 in their group match against England earlier this tournament, they still lost by over 70 runs.

There might be a time in the future when South Africa can be a legitimate and constant threat to England, but it wasn't meant to be now, not today. England planned on approaching this like a tough training challenge, and expected to win easily.

***

Jenny Gunn comes out to bat with England needing 46 off 46 balls, but she brings out a different pitch to everyone else. Her English team-mates have been playing on a slow pitch that means you hit the ball into the hands of a fielder in the ring. Gunn manages to find gaps, she is constantly on the move, she scores more twos than had seemingly been scored all match, and when she needs to find the boundary, she can do that as well. She is batting at more than a run a ball, which in a game like this, is some kind of magic.

And now, in the final over of the contest, she needs only three more runs to win the game and send her team to Lord's for the final. Shabnim Ismail steams in, the self-proclaimed quickest woman in the world, she aims full and straight, so Gunn just smashes it. The noise is so obvious, the ball has been crushed, but it has been hit straight back at Ismail.

There is no time even to think about the catch, even to wonder what if. It is already on the ground, dribbling away from South Africa. Gunn is still there, just.

***

South Africa's real big chance of winning this game came when Lizelle Lee and Laura Wolvaardt embarked on what they hoped would be their third 100-run partnership of the tournament. Lee had been hitting sixes for fun all tournament - seven alone in the victory over India - while the TeenWolv has been dismissed for less than fifty once in the entire campaign. But Lee was out before they could get off to a flier, and Wolvaardt was slowed down by spin, scoring only nine from her first 30 balls from it. England won both the early battles.

England don't push hard for wickets in the middle overs, and they didn't today. It was only when Wolvaardt missed a fairly standard straight one that they picked up a wicket. In the same over Mignon du Preez hit the ball straight to cover and Marizanne Kapp was run out. Ten overs later, they lost another wicket to another silly run-out, and doubled up by losing another wicket the next over. It's not hard to restrict the opposition when they so frequently run themselves out.

South Africa were, at best, 30 runs short, and probably 50 short. With a good opening partnership, and Nos. 3 and 4 being sensible, the match would be won with overs to spare. Easy.

***

It's come down to England needing three off five; it should still happen. Ismail goes wide of the stumps, she takes the pace off it, all Gunn can do is aim it into the packed offside field, which has seemly every woman born in South Africa trying to save the one. Dane Van Niekerk attempts to stop the single, but she can't.

And now England need two runs off four balls, but Jenny Gunn is off strike.

England started well; they scored quickly. South Africa dropped catches and bowled wides. There was no real pressure. The pitch might have been slightly trickier than anyone had yet admitted, but this was not a tough chase, England were ahead the rate and, at the end of the first ten overs, they had cruised along to 52. Sarah Taylor's first ball was a cover drive off Ayabonga Khaka, which went away to the rope like it was being dragged there by magnets.

Taylor was in complete control; she was batting like the woman who was once supposed to take over women's cricket. The runs came off her bat with some indefinable extra authority, as if every run was saying, 'not only am I scoring, but I am fundamentally better than you in every way that matters'. Her innings felt like a sparring match between a world-class heavyweight and a punch-by-the-hour battler brought in to make the champ feel better.

The last shot she played was a flick past mid-on that seemed almost obscenely easy. She didn't play another shot after that because Heather Knight ran her out.

The wicket shouldn't have meant much, Knight was still in, there was plenty of batting to come, and it was only the third wicket of the innings. But suddenly Knight was out as well, and the easy day, the better team, none of that meant much any more. This was now a sudden-death game, and England had never been closer to death.

***

Laura Marsh has a top score of 67 in ODIs; this matters as she faces up to Ismail with two runs needed off four balls. Her career average of 13 has never looked so shaky. England back themselves to bat all the way down, but teams always say that. No one really means it, and those words mean nothing when you need two off four against one of the best bowlers in the world.

Ismail's ball is full and straight. Marsh, her top score of 67, and her average of 13, are nowhere near it. Her shot is an awkward shuffling paddle that she might as well have played in Taunton and not Bristol; she'd been about as close to the ball as she was to the town. Ismail lets out a scream as the ball hits the stumps. This is not a drill, England have won six on the trot coming into the game, kept the world's sixth-ranked side to a sub-par score, and are now three good balls from not making the final. This is not a drill.

***

Katherine Brunt has been begging to bat up the order for years, and this was the sort of situation that she loves the most. When it's tough, when it's tense, when every run is like a spit in the eye of your opposition, the contest could not be better set up for her. In having a player of such experience and talent in their middle order, England has a huge advantage over the other teams. But not this time. Nothing was working for her today.

Brunt bats up the order in T20 games, but in making two runs from eight deliveries - and 12 from 27 all told - she was looking less like a T20 hitter and more like an ODI misser. To make up for her struggles she charged down the pitch to Daniels, and instead of toughing out a boundary, or breaking the game with her aggression, she was bowled.

It was left to Fran Wilson to play balls over her head and reverse-sweep the spinners out of the attack while marshalling the specialist bowlers. But Wilson tried one scoop too many - England were all out of specialist batting, and almost all out of the tournament.

Anya Shrubsole takes an age to make it to the middle. There is no doubt she wasn't planning on batting. She wasn't planning on batting when they restricted South Africa to 218, she wasn't planning on batting when they got off to a flier, and there was no way she was thinking she'd bat when Taylor and Knight were strolling to victory.

England only need two runs, but this has been anything but a perfect performance. They didn't push hard enough with the ball in the middle overs; they gave away too many runs in the field; none of their top order went on to complete the job; they had another stupid run-out, and then their middle order got behind the rate and panicked. Even now, with Shrubsole coming out, it's hard not to think that England might rue Gunn's single off the second ball of this over. The best chance of winning the game is stranded at the non-striker's end on a run-a-ball 27 not out.

Shrubsole crouches over her bat, looking anything but a player who is about to hit the winning runs. Ismail hits the crease and Shrubsole suddenly relaxes, takes two steps down the wicket, and hits the ball through point in a flash. It's incredible, beautiful, strong. The South Africa women fall to the ground and cry, Shrubsole jumps onto Gunn.

"We're finding ways to win" says Knight, England's captain. For most of the day, it looked like they were finding ways to lose. England weren't planning on it being this close; they weren't planning on almost losing, this wasn't a training match, a bye, or a perfect performance. It was a win off the third-last ball, from the No.10.

England didn't win easily. But they won. If they get to sing in the holy dressing-room of Lord's, today will be the tough one they laugh about as they belt out their victorious anthem. There is only one more win between them and the sweet drunken merry sound of success.