Further to Jack's comments about the George Cross, the bar for this award has been set incredibly high, and rightly so. This is reflected in the fact that since its inception in 1940 it has only been awarded 161 times, and a large proportion of those awards took place during WW2. There have only ever been four awards to women, the three well-known awards to SOE operatives Odette Sansom, Violette Szabo and Nora Inayat Khan (the last two posthumous), and the posthumous award to Barbara Harrison, a BOAC stewardess who died whilst helping passengers to escape from an onboard fire at Heathrow. Although originally intended as a civilian award, military recipients far outnumber those to civilians, and in fact the last civilian award was in 1990 to a New Zealand policeman.
I assume P-N's remarks about grammar school teachers were made tongue in cheek, but I hardly think that the type of educational establishment she worked in came into it when considering what award Lisa Potts would be given!