It definitely sounds like you were in the wrong part of the room :)
A problem people have mentioned before is actually finding all of the HNers amongst the other drinkers, so you're not alone. Because of this we started looking for an alternative venue but we couldn't find anything suitable in time.
If you've got any suggestions it'd be great if you could let us know, either here or via the Google Group: http://groups.google.com/group/hn-london/browse_thread/threa...
For the event this Thursday we'll put up a sign, which should at least help you find the right area of the bar.