* The Domesday Book: The Domesday Book, a census of England completed in 1086, shows that Clapham's population had declined by about 25% since 1066. This suggests that many people had either died or left the area.
* The decline of the local economy: The Domesday Book also shows that Clapham's economy had declined after 1066. The value of the manor had fallen by about 50%, and there was less land under cultivation. This suggests that the Normans had taken over much of the land and were not investing in the local economy.
* The increase in crime: The Domesday Book also shows that crime had increased in Clapham after 1066. This suggests that the Norman Conquest had disrupted the social order and made it easier for criminals to operate.
As for what may have happened during the march to London, there are several possibilities. One possibility is that the Normans simply pillaged and plundered the countryside as they made their way to London. Another possibility is that the Normans engaged in a scorched earth policy, destroying crops and burning villages in order to deny the English supplies. Whatever the case, it is clear that the Norman Conquest had a devastating impact on life in Clapham and the surrounding area.