Glad I'm not the only person that feels this way. London I've found is generally quite a friendly city when you're in pubs/clubs etc, but it's impossible to really make friends the old fashioned way because it's so vast - half the time you meet someone they turn out to live on the other side of town. And whilst that's OK for long-built friendships, it's not so conductive to making new ones - I manage to see my friends who live on the other side of London twice a month if I'm lucky, you don't really build new friendships with such sparse meetings - that leads to a rather lonely existence the rest of the time.
I'd love to make it to your April 20th meet-up, but unfortunately I have exams the week after.