Victorious England nowhere near the finished article, insists Cook

A trio of match winners in Stuart Broad, Joe Root and Ben Stokes offer England a bright future in Test cricket but unfortunately for Alastair Cook, there seems to be no end in sight in his long search for a worthy opening partner.

Knocking South Africa off the top of the Test rankings following the 2-1 series triumph comes close to the drama of last year's Ashes success over Australia, captain Cook said.

The victories achieved in first and third Tests "ticked a box" for a relatively new generation of stars. Broad's bowling decimated South Africa in the third Test in Johannesburg to secure the series triumph.

Stokes, 24, was an unstoppable force with the bat in the second Test in Cape Town, where he raced to the quickest 250 runs in Test history.

Root, 25, turned into Mr Dependable during the series, scoring at least a 50 if not better in each of the four Tests. But Cook insisted England are "nowhere near the finished article" after they ended the series on the receiving end of a 280-run defeat by the hosts -- which ended South Africa's year-long wait for a Test victory.

Looking ahead to home series against Sri Lanka and Pakistan, Cook said: "We still have a lot of work to do with our batting and catching." England suffered plenty of woes in the field throughout the tour and Jonny Bairstow's wicket-keeping skills were also not up to the mark.

However, even more vexing is the question of a reliable long-term opening partner for Cook, who has walked out with eight different players in 39 Tests since Andrew Strauss retired in 2012.

The latest incumbent, Alex Hales, offered little evidence that the search is about to end.

The 27-year-old opened in all four Tests but returned an average of 17, top scoring with 60, and there is every chance he could be dispensed with by the time the first Test against Sri Lanka starts at Headingley on May 19.

England coach Trevor Bayliss said he wanted to see a more aggressive top order, which might end Nick Compton's tenure at number three.

But there are plenty of things that are working in perfect harmony in the England set-up.

On the man-of-the-series Stokes, Cook said: "I think he has thrived under pressure and thrived working under Trevor Bayliss.

"They get on really well and have this strange relationship where they swear at each other."