http://ftalphaville.ft.com/blog/2007/04/11/3730/insurers-launch-%E2%80%98london-flood%E2%80%99-bond/

This helps them to offset some of their risk if Canary Wharf and surrounding areas are flooded. In theory the Barrier should protect us for a few more years

http://en.wikipedia.org/wiki/Thames_Barrier

although a combination of a spring tide and severe storm similar to 1953 could breach the barrier and flood defences

There has been a book written about a fictional flooding

http://www.floodlondon.com/floodtb.htm

http://www.amazon.co.uk/exec/obidos/ASIN/0099429691/floodlondonco-21

and the pre-barrier original

http://www.amazon.co.uk/Deluge-Richard-Doyle/dp/0330252577/ref=sr_1_1/026-9670453-0954038?ie=UTF8&s=books&qid=1176373493&sr=1-1

and there was a documentary on BBC2 a few weeks ago

http://www.discoverychannel.com.au/perfect_disaster/mega_flood/index.shtml