I'd be a little cautious about the domain name and the singling out of presence of beer and pizza (over other characteristics of the event). This just reinforces biases within our industry, without mentioning all other perks.
What about people who do not care about beer and pizza but care about London startup events?
What about the actual content of the meetup?
I dearly hope they aren't "cautious" about enjoying beer and pizza. It's a perfectly normal thing to have at an event for adults.
These kinds of things are cool but they usually last maybe 4-6 months then fall fallow as no one bothers to update them. The feeds are the worst since there's no UI interaction point - the feed just becomes quieter until people forget about it.
Cool! One thing though - pleeeease don't scroll hijack :-(