Thunder storms and heavy rain have caused flooding in south east England, with 550 emergency calls made to the fire service overnight on Wednesday (local time).
Over 400 incidents were attended. Flooding of roads and housing as well as lightning strikes were the prevalent reasons for the call outs.
Several London Underground stations were closed after 40mm of rain fell in some places, the BBC reported.
"It's a very fast moving picture this morning, with flash floods still arising and others falling in a variety of different routes into London," a Network Rail spokesperson said.
Flood waters rose steadily around midnight in London and eventually came to flow at knee height in some parts.
All this threatened voters heading to the polls as Britain decides whether to stay or leave the European Union.
Showers are expected to ease for most of the country on Friday.