The activation - created overnight - featured penguin, polar bear and reindeer statues as well as a snow machine.
Ahead of the surprise, RPM launched a picture competition asking the childred to draw "the true magic of Christmas". With those images, the agency also created a countdown to Christmas.
Ryan Thomas, creative head at RPM, said: "The thought behind this was that we're actually based in the heart of the community in Shepherd's Bush and we wanted to do something that really incorporated the whole community and get them involved."