I agree with you about the tech scene. For example DevTank (the tech counterpart to DrinkTank) has been excellent so far. The London BarCamps are also great, as are the Hack Days.

I also agree that the start up (and also the mobile) events aren't terribly useful. They are more of a nice place to relax in the company of like-minded individuals rather than places to generate business.

As for boozing... that's just London in the evening. Most people are bright enough to stick to one or two drinks and you still see everyone in the office at 7.30am the next morning.

By comparison I found events in New York to be a little free of personal interaction. You turn up, spend 5 minutes talking to 5 people, listen to a speaker, then go home. Great for collecting business cards, not so good for establishing solid relationships. Perhaps someone can suggest better events for me?