 This was utilised for the first time during the 2011 race as casualties at fences 4 and 6 (Becher's Brook) resulted in marshals diverting the remaining contenders around those fences on the final lap.Welfare groups have suggested a reduction in the size of the field (currently limited to a maximum of 40 horses) should be implemented.Opponents point to previous unhappy experience with smaller fields such as only 29 runners at the 1954 Grand National, only 31 runners in 1975, and a fatality each at the 1996 and 1999 Nationals despite smaller fields, and the possible ramifications in relation to the speed of such races in addition to recent course modifications (part of the "speed kills" argument).