Where to meet people your own age in london in your 20s

What do people in their 20s do in their spare time after graduating from uni in London? Everywhere in London (whether bars, interest/hobby groups, parks etc) is full of people over 30 or uni students. So where is everyone aged 22-29? Where do you meet people your own age?

Twenty something Londoner here so fortunate to already know some others living here plus a couple of uni friends moved down too. Most of my socialising recently has taken place in either a cafe, restaurant or someones house with occasional trips to pubs/bars. I have seen other 20 somethings in some places. Clapham was teeming with them and I also saw other 20 somethings in the Spanish Bar in Soho I went to and a nightclub in Covent Garden after 11pm. Also Box Park Shoreditch when I went last year was almost exclusively dominated by 20 somethings. Social media tells me East London day festivals and gigs are also popular as well. That said the only new 20 somethings i've met have been through work and friends of friends, its virtually impossible to meet other 20 somethings on your own as all the ones who go out have fixed friendship groups.