Have to laugh at all this talk about England being anywhere near South Africa. The last series between them had SA dominating them 3 out of 4 tests, and the series before that in England SA won 2-1. England flatter to deceive, are hyped up by their press, and this current side isn't as good as the Ashes 2005 that was supposed to conquer the world.
People seems to forget that a team doesn't become number one by having a good few series at home and crushing some weak opponents like Pakistan. To be decisively no.1 you need to have sustained success and be able to be world beaters outside of home. You don't become no.1 based on random speculation how you might do against an opponent with no record to back it up.
South Africa are the only team that qualify for number one, partially due to the weakness of others outside home in the recent past. Since 2007, SA have under Smith beaten Pakistan, England, NZ, WI, and Australia outside and drawn two series with India (the most difficult place to tour) with pretty much the same nucleus of a team they have now. The only blemish has been their loss to Australia at home in 2009.
Compare that with India under Dhoni who have won a string of home victories but have only beaten a Bond-less NZ and seem ready to lose to Sri Lanka outside, and Australia under Ponting who have lost to India, England, and SA in the past two years. England under Strauss have won the 2009 Ashes and were lucky to escape with a draw in SA. If they can manage a draw in Australia then perhaps we can talk.