I did however come across a section devoted to the different types and amounts of armour used and when it was introduced.
I wasn't too surprised to find that the Polikalov I-16 was the first fighter to have armour, albeit a single 8mm (5/16") plate behind the pilots headrest.
But to my utter surprise I learnt that all the Hurricanes and Spitfires that took part in the Battle of France (May - June '40), and this included basically the entire compliment in the RAF, had absolutely no armour at all.
Armour was hurriedly fitted (after a few lessons were learnt, I imagine) before the BoB got under way about a month or six weeks after the fall of France.
A very fortunate 6 week break for RAF pilots, I dare say. ;D
