Travel time is a little bit over 1 hour.
There is a time difference, so you arrive in London time almost the same time you left Brussels.
There are many daily
flights between Brussels
(BRU) and all airports of London in 2009.
The eurostar train is a very good alternative to air travel if your final destination is London.
There seems to be a daily flight with British airways at 12:10 noon from BRU to London Heathrow
(LHR) in 2010. You can then catch a transatlantic connecting flight in