By Martin Domin I Am Maximus has won the Grand National. In the day’s opening race, Dan Skelton improved his already impressive record in handicaps at the major meetings when Gwennie May Boy continued his rapid improvement in the William Hill Handicap Hurdle. Having won the Grand Annual and Coral Cup at Cheltenham with Unexpected Party and Langer Dan respectively, Skelton plundered another valuable prize on Merseyside with Kateira on Friday. Last year’s winner West Balboa appeared the stable’s first string in the Grand National day curtain-raiser, going off a well-backed 11-4 favourite under t…