are hoping for as many supporters as possible to help get a huge crowd of people to show Julian and WikiLeaks that they stand in solidarity.
The event starts at 6:30 pm (GMT) with songs of solidarity lead by the South London Massive, singing their hit "I shall be released!", along with VFPUK, Lovers Electric and the Vigiliers All.
Assange will start the speech to mark the 6 months of his imprisonment at the Ecuadorian embassy at 7:00 pm local time (GMT).
Supporters should bring candles and food.
A map and directions can be found on the Facebook page
for the event.