There is often plenty of play in equal looking king and pawn endgames unless the position is blocked.

The world chess champion Magnus Carlsen demonstrated this at Wijk aan Zee in January when he took advantage of a lapse by women’s world champion Hou Yifan.

Hou Yifan has just played 45...h5?? when 45...a5 was essential and after 46.b4 Ke6 47.bxa5 Kd7 48.Kb3 Kc7 49.Kb4 Kc8 50.Kc3 Kd7 Black’s position is impregnable and she makes a draw.