As it "advertised" on the web: The last day of legal sub-level inebriation, which basically meant another reason for a circle line party on the underground.
Saturday was the last day you were allowed to drink on any of London's transport routes, so as a farewell to this, tens of thousands of people joined in the circle line party to drink away to a previous luxury.
Eventually, after severe delays and defective trains and various station closures, the circle line was shut and all party goers were turned away just before midnight, when the ban was to set in. We made it half way round the circle line, which was great, just a mission getting back with limited tubes :) But I feel I was part of history. Well, until they bring back drinking on the tube and all of London has a welcome-back underground party! Good times...