As of 2004 or 2005, the majority has shifted from air travel to the Eurostar. Business commuters, especially, have been pleased with the convenience and speed of the train.
The trend towards Eurostar continues with nearly twice as many passengers from in and around London using it compared with flights. The advantage of Eurostar is that it goes from the centre of London to the centre of Paris and vice versa - and there is no checking in and less security. Both can be expensive but the trick is to book well in advance if you can. I regularly use Eurostar to go to Paris to update my Paris city guide and my mp3 tour of Paris and its most famous sites.