Meetup groups are a worldwide phenomenon, and thriving. They cover all kinds ofinterests. Take the East Midlands Dungeons and Dragons Meetup. Preferably to a safe distance, please.
The LondonJazz Meetup, run by occasional LondonJazz writer and thumb-popping bass nut Rob Mallows now has 620 members, and organizes groups to go to loads of London gigs. They also have gatherings. The next is at the Archduke in SE1 on August 7th and here are the details