Whakakihia te rerenga e whai ake nei: Mai i Eton, i uru a Grigg ki te ope taua o Ingarangi, a, i whakawhiwhia ia hei tuarua tuarua ki roto i te ope taua a tona papa, nga Grenadier Guards, i te 1943 i te Pakanga Tuarua o te Ao (1939<unk>1945). I a ia e mahi ana i te ope taua o Ingarangi, i mahi a Grigg hei rangatira mo te Tiaki i te Whare o St James me te Whare o Windsor, Berkshire, ana i kite ia i te mahi hei rangatira pluton i te 1st Battalion, Grenadier Guards, he waahanga o te 5th Guards Armoured Brigade o te Guards Armoured Division, ki te ope taua Tiamana i
France me Belgium. I te mutunga o te pakanga, ka noho ia hei rangatira matauranga.