Since their readmission to international cricket in 1992, South Africa have played ten Test series against England, five at home and five away. They have won four and lost three, while three have been drawn. In England, they hold a 2-1 edge, with two series being drawn, while in South Africa the two teams are level 2-2. In terms of Tests won, South Africa are marginally ahead 14-12, with an 8-6 edge in England, and a 6-6 record in South Africa.
If these numbers suggest two closely matched teams, then consider this: in the ten series between them since 1991, neither team has won two series in a row against the other. In the last eight series, going back to 1998, the series outcomes have followed this pattern: England, South Africa, draw, England, South Africa, draw, South Africa, England. (Going by that sequence, this should be a drawn series.) Also, only once in these series has the victory margin been more than one Test: in 2012, when South Africa won 2-0 in England. Admittedly, there have been a few instances when the losing team has achieved a consolation win in the last Test after the series has been decided, but even so, there has been little to choose between the teams, and a 14-12 win-loss record (in favour of South Africa) indicates the narrow margins.
Other rivalries have evoked more passion, more romanticism, more history, more media coverage, and more hype, but in terms of closeness of rivalry in the last two and a half decades, look no further than England v South Africa in Tests. No contest has been closer, and in no rivalry have home conditions mattered so little.
Among all the team head-to-heads in Tests since 1990, there have only been four others in which the win-loss ratios have been as close or closer. In 15 Tests between India and Pakistan, each team has won five, with five being drawn. That's the perfect symmetry, and it gets even better when you look at the match-wise results: each win-loss sequence has been in a pair, one following the other immediately. That is the perfect rivalry, except that those teams haven't played each other in Tests in almost a decade.
The Pakistan-Sri Lanka rivalry is another one with a near-perfect symmetry: Pakistan have a 14-13 edge in 42 Tests, with 15 draws. They have a 7-6 lead in Sri Lanka, 4-6 deficit in Pakistan, and 3-1 lead in the UAE, which has been their "home" in the absence of any Test cricket in Pakistan. However, the India-Pakistan and Pakistan-Sri Lanka rivalries are both intra-Asian, which means conditions remain fairly similar when playing home and away.
The two others are in the top five are India-England (14-13 in favour of India) and Australia-India (21-18 to Australia). Unlike the other rivalries mentioned earlier, though, these ones have been heavily loaded in favour of the home teams: against England, India lead 11-3 at home, but are 3-10 in England. Similarly, Australia have been utterly dominant against India at home, with a 16-2 win-loss record; in India, though, they have been quite dismal, winning five and losing 16. In each of these two cases, the overall numbers look deceptively close, but each team does a majority of its winning at home.
Not in the case of England-South Africa, though. Both teams have won plenty in opposition territory, especially recently. Till 2000, both teams were more successful in home conditions, but since 2000, they have each won more in away series: South Africa have won each of their last two series in England, and England have won two of their last three in South Africa. Since the start of 2003, England have a 5-3 win-loss record in South Africa, while South Africa have a 6-3 record in England. In fact, South Africa have won exactly two Tests in each of their last three series in England.
The major improvement for South Africa on their recent tours to England has been their batting: on their first couple of tours they averaged only 34.81 runs per wicket, but in their last three, that has gone up to 43.54. Even though the bowling average has gone up as well, the lift in batting numbers has allowed the bowlers enough opportunity to pile the pressure on England's batsmen. After managing only six hundreds in their first eight Tests in England, South Africa's batsmen scored 18 in their next 12.
The two pillars of South Africa's batting in England have been Hashim Amla and Graeme Smith. Smith scored five hundreds - including two doubles - in 12 Tests in England, and averaged 67.75, but England need not worry about him any longer. The batsman that they will worry about, though, is Hashim Amla: in 12 innings in England, he has three hundreds - including an unbeaten 311 - and averages 75.70. In two Tests at Lord's, he has two hundreds, both in the second innings. Moreover, he has excellent records against England's two biggest threats, James Anderson and Stuart Broad, especially in England.
England, meanwhile, will hope that a relatively inexperienced South African top order isn't as deadly this time around: AB de Villiers isn't there, and Faf du Plessis is missing the first Test. That should help them overturn what has been a pretty dismal Lord's record against South Africa: in their last five Tests here, they have lost four. That is just another stat that illustrates the topsy-turvy home-away numbers in England-South Africa Test matches.