#5 England lacked the presence of a true playmaker
Since Southgate had gone with a 3-5-2 formation, there was no true no.10 playing between the lines. With Jordan Henderson in a deep midfield role, England had two no.8s in Dele Alli and Jesse Lingard.
While both players are two bundles of energy on the run and effective on coutner-attacks, they lacked the vision to split open Tunisia's defence in the second half when they were content to sit back and absorb England's pressure.
Alli tended to drift wide to the left in search of space while it was Sterling who dropped deep to receive passes from midfield in an attempt to advance the ball forward. Neither of the strategies worked as Kane was devoid of any real service.
Southgate did try to change things with 10 minutes to go when Alli was taken off for Ruben Loftus-Cheek. He didn't have enough time to make much of an impact but his positioning and movement did cause problems for Tunisia and he did create one good chance that was fluffed in the dying minutes of the game.
Nevertheless, it was another set-piece that allowed England to score the winner with Harry Maguire heading a corner to the far post where Kane headed home the winner.