The agency has set up a Christmas lights display, which is powered by a bike, in the front window of its 81 King's Road offices in Chelsea.
Richard Marshall, founding partner and chief marketing officer, cycled the first 15-minute stint on the bike at 9am this morning.
Staff will cycle until Christmas Eve to raise money for a Tanzanian village close to the heart of Costella, who died of cancer aged 38, and his wife Kate.
The money raised will go towards the provision of street lighting in Fundu Village.
TMW is taking donations on its website, where people can watch a live stream from a webcam trained on the cycle.
This article was first published on brandrepublic.com