London Book Fair

Appointments all the way. There's a bit of informal networking but generally people are too busy to hang about chatting when there are deals to be done.

Torgo pretty much summed it up.

As others have pointed out, it's appointments all the way. 15-30 minutes each, I believe.
Few deals are originated AND done at London -- the ones that are finalized there are the result of editors receiving the manuscript ahead of time; the ones that originate there are finalized once the editors have had a chance to read the manuscript after the fair. The few exceptions to this generalization are the deals that make headlines...
My agent has a catalog of her available clients/works, which she uses during her appointments, following up areas of interest later.

*** Monica, feel free to correct me if I have any of that wrong.

There are lots of appointments, very long days, and surprisingly little socialising (considering how very sociable most of the agents I know are).

There is a whole area of little tables set up--it looks a bit like a giant school canteen--for agents and editors to meet.

Books are pitched; very few deals are finalised, as contract negotiation usually takes time. But it does happen.

Agents tend not to carry mss around with them, as they're just too heavy and there's no need to do it: they can swap flash-drives or send them by email, for example. And if they DO need a printed copy they can get one couriered to them in an hour or two, or print one out at the copy-desks.

It's a high-energy fair, and wonderful to visit: but don't expect to go there as a writer and find an agent or editor willing to talk to you. They just won't have the time. And yes, there is a hierarchy: established agents and editors have far too many people trying to meet up with them, whereas the less well-known ones will have more free time.