Well, this is how I used to go to free parties in London… connections through the squat/homeless scene. Because the crews are pretty much off the radar, but they need links into different social circles to tell people where the next party is.
I found the best flyers were the most plain and boring looking ones.
I would guess that, while the crews have changed people several times since then, the principle is the same – march through the West End and ask every beggar and Big Issue vendor you come across if they know about any free parties.
If they say yes, offer to give them some cash at the party (to avoid being ripped off on the spot).
Hope this helps. I dare say things have changed a bit, but I doubt they’ve changed that much in terms of outsiders getting in to free parties.
EDIT: Yes, I was one of the BI vendors in the West End. Long time ago.
