So South Africa lose again. All England need to do is beat them in their face off and England go through to the semis while South Africa … well … they go where they deserve. If South Africa win that match though, they are a guarantee to go through.
South Africa have a two point lead on England, with their final match against the Poms. England have two matches left, their other against the West Indies. Even if England go on to lose against the West Indies, but manage to beat South Africa (which is in the realm of possibilities given South Africa generally crack under pressure), England currently have (and probably will maintain) a better run rate.
This is a rare occasion, but I will be cheering England home.