By Kate Green The two leading riders in the FEI Classics™ 2013/2014 go head to head in the fourth leg of the series, the Mitsubishi Motors Badminton Horse Trials (GBR), this weekend (8-11 May). William Fox-Pitt, winner of Pau (FRA) last year and Kentucky (USA) last month, and Christopher Burton (AUS), who triumphed on a