There's also this Chris -

http://www.guardian.co.uk/science/story/0,,2129662,00.html Part of the article reads -

"...a second massive flood completed the job of separating Britain from France around 180,000 years ago. Another vast glacial lake formed from rivers off the east coast of Britain and was temporarily contained to the south by an earth ridge spanning from north of the location of present-day Ipswich across to a point which is now The Hague. Water released into the Dover strait widened the channel to more than nine miles in some regions.
"Philip Gibbard, a geologist at Cambridge University, said the megafloods that created Britain were on a par with the largest known on Earth, including an event that created Lake Missoula in Washington state at the end of the last ice age.

"The second flood followed less severe glaciation and may have been witnessed by early humans..."