The first lesson one should learn once they reach cruiser and above is not to judge the ship’s survivability by numbers on paper.
QE class without modernisation has very weak deck protection, and they lack splinter protection directly over the magazine like the Hood and Renown has, and one can easily get caught in such situation:
In case of Renown this would not be fatal:
Spoiler
FYI 40 lbs = 1inch/25.4mm of armour
This is why Bayern-class in game can be often ammoracked despite it has 350mm armour belt plus 80mm slope deck, because the much vulnerable barbette can be penetrated easily and the splinter can go all the way down into the magazine. Renown on the other hand rarely die from ammo explosion despite their belt on paper is only 229mm. The nuances in armour placement play a much more important role in the ship’s survivability than raw numbers of armour thickness in WT’s highly detailed DM.