As Joe Root prepares to play in his 100th Test match, Jonathan Agnew speaks to the England captain to look back on his career, his Test debut, and to ask what the future holds. Sir Alastair Cook says he has no doubt that Root will surpass his record total of Test runs, whilst Michael Vaughan thinks that he will become England’s greatest ever batsman. Plus we hear from his parents, Matt and Helen, on what a cricket-obsessed Joe was like growing up.