Regarding numbers, 240, 000, or 10% of the population of Brittania, seems way too high.
Regarding contact period, 6 hours seems a short period for a killing orgy.
Regarding method, I was thinking maybe 50% of casualties were at a distance, i.e. archers, sling stones, ballistas, scorpios, kitchen sink etc..... The topographical description suggests to me a dense mass of Brits being pelted from above. It'll be a nightmare to find evidence if a large proportion of that material was rough hewn stone..... that would be an economic way to dispatch all comers in relative safety and fits the description for me..... did I mention the ridge top stone quarries at Church Stowe? Maybe geology is a re-provisioning factor that needs to go into the matrix along with perched water tables (I suspect no support from the mudstone and chalk candidates - too soft)
Regarding contact period, 6 hours seems a short period for a killing orgy.
Regarding method, I was thinking maybe 50% of casualties were at a distance, i.e. archers, sling stones, ballistas, scorpios, kitchen sink etc..... The topographical description suggests to me a dense mass of Brits being pelted from above. It'll be a nightmare to find evidence if a large proportion of that material was rough hewn stone..... that would be an economic way to dispatch all comers in relative safety and fits the description for me..... did I mention the ridge top stone quarries at Church Stowe? Maybe geology is a re-provisioning factor that needs to go into the matrix along with perched water tables (I suspect no support from the mudstone and chalk candidates - too soft)