How to take a 6-figure grid reference with Steve Backshall and Ordnance Survey

GetOutside champion and naturalist Steve Backshall continues the previous video on 4-figure gird references at https://www.youtube.com/watch?v=c0du8v4EE_Y by explaining how to enhance this to a more accurate six-figure grid reference: SU 265 166 A six-figure grid reference allows you to give a position accurate to 100m for a feature on a map.