Vaughan - leader of the pack.
Michael Vaughan (captain, age 33, caps 78).
Struggled for consistency since last summer's triumphant comeback from a long-standing knee injury and his century against New Zealand at Lord's was his first for 15 Test innings. Has scored only one hundred in 14 Tests against South Africa but will be keen to improve on that record given his obvious dislike of rival captain Graeme Smith.
Alastair Cook (23, 30).
One of the many members of England's top order who has struggled for form recently having scored only one century in his last 24 Test innings. Averaged just 30.80 in the six recent Tests against New Zealand in home and away series and his form will not have been helped by missing several weeks of cricket during the one-day series with a shoulder problem.
Andrew Strauss (31, 49).
Has enjoyed a successful return to the Test side since winning his place back in New Zealand after being dropped for the tour to Sri Lanka before Christmas. Averages 54 since his recall and his experience at the top of the order alongside Cook will be crucial to England's success against South Africa's formidable pace attack.
Kevin Pietersen (28, 39).
Has never played a Test against the country of his birth and his confrontation out in the middle against South Africa will be on the most intriguing factors of the four-Test series. Tends to be inspired by the bigger challenges as he proved three years ago when he hit three centuries in six matches in his maiden one-day series against them.
Ian Bell (26, 39).
Encouraged to increase his stature as an international player a year ago by England's management, Bell has struggled to make the step up from a player of great promise to a major player. He is one of four members of the top six to average less than 40 in the last year and if endures a difficult start to the series, his place could be under threat.
Paul Collingwood (32, 36).
Another player under pressure for his place after going 23 Test innings since his last century, during which time he has averaged just 31.65. His early form during the one-day series against New Zealand hinted at a revival before he received his ban for slow over-rates but needs an early innings of note to prevent pressure building on him.
Tim Ambrose (25, 6).
Has yet to really establish himself as England's wicketkeeper after replacing former Sussex team-mate Matt Prior behind the stumps for the tour to New Zealand earlier this year. Scored a crucial century in Wellington to help win that Test, but has averaged only 30.44 in his six Tests. Needs to score more consistently if he is to withstand a renewed challenge from Prior to reclaim his place.
Ryan Sidebottom (30, 16).
England's best bowler since being recalled for the second Test of last summer, six years after his only previous appearance, and has claimed a staggering 70 wickets in the 15 Tests he has played since. His success or failure against South Africa's top order will be a key factor in whether England prosper or suffer their second defeat in the last three home series.
Stuart Broad (22, 6).
Has made significant progress as an international bowler since England made the bold decision to drop Ashes heroes Matthew Hoggard and Steve Harmison and keep faith with a younger, more vibrant attack. Has also contributed useful runs down the order batting at number eight, but faces the biggest challenge of his career so far against a South African side far stronger than New Zealand.
James Anderson (25, 25).
Recalled alongside Broad during the tour to New Zealand earlier this year, Anderson has relished his extended run in the side in the five matches since. He has taken 27 wickets at just 24.07 during that period, including a career-best seven for 43 in his previous outing against New Zealand at Trent Bridge. Claimed 15 wickets the last time South Africa toured England in 2003 and will be hoping for a similar return this time.
Monty Panesar (26, 29).
Has never played a Test against South Africa and the drier pitches in the second half of the summer should be to his liking. Has already demonstrated his ability to perform when conditions suit with a career-best six for 37 against New Zealand at Old Trafford. As an unknown quantity to South Africa's top order, his influence could be a key one to determining the outcome of the series.
Andrew Flintoff (30, 66).
Would have featured at the start of this summer against New Zealand but for a side strain suffered just before the first Test at Lord's. Has impressed with the ball this season since coming back from ankle surgery, but has struggled with the bat and his return for England may be dependent on him batting down the order until he rediscovers his form.
Ravi Bopara (Essex) (23, 3).
Dropped from England's Test ranks after an unconvincing first series in Sri Lanka before Christmas when he scored only 42 runs in five innings. Has rediscovered his form in county cricket and although he had an inconsistent one-day series against New Zealand, remains the next batsman in line should England decide to change their stuttering top six.
Owais Shah (29, 2).
Toured both Sri Lanka and New Zealand during the winter but failed to play a Test as England kept faith with their settled top six. England's best batsmen during the recent one-day series against New Zealand, Shah has waited patiently to play his first Test since the start of last summer.
Steve Harmison (29, 56).
Dropped after an unconvincing first Test against New Zealand at Hamilton, Harmison has been on the periphery ever since. Has continued to play for Durham but the extra pace and bounce he can provide even on placid pitches when he gets it right always keeps him in contention for an England recall.
Chris Tremlett (26, 3).
Enjoyed an impressive series against India last summer, claiming 12 wickets in three Tests, and looked set to force his way into the side on a permanent basis during the winter. Once again, though, injuries have restricted his progress although England indicated he remained in their plans by including him in their squad earlier this summer.
Matthew Hoggard (31, 67).
Dropped after a laboured display in the opening Test against New Zealand in Hamilton, Hoggard has struggled to force his way back into the reckoning although he was included in the squad for the opening Test at Lord's. Injuries have interrupted his progress at county level but retains a fierce desire to force his way back and reclaim his place.
Matt Prior (26, 10).
Dropped after a series of wicketkeeping mishaps during the tour to Sri Lanka before Christmas, Prior has knuckled down and performed well at county level to keep his hopes of a recall alive. Still averages over 40 at Test level and has worked hard at his wicketkeeping skills with former England captain Alec Stewart.