She is most widely known for pouring green custard on the then Business Secretary Lord Mandelson in March 2009 in protest against the extension of Heathrow Airport, for which she was arrested and cautioned.
[2] Deen was a prominent member of anti-aviation group Plane Stupid and a campaigner for the World Development Movement, focusing on water,[4] finance, and climate change.
[6] She was quoted as saying "The crumbs of debt relief and aid increases... remain tied to debilitating conditions, which stands in direct contradiction to Make Poverty History".
In contrast to her later direct action, at the 2008 Kingsnorth Climate Camp Deen was reported to be "keen to stress that WDM does not support illegal protest methods".
[10] As a member of Plane Stupid, she dressed as a suffragette, glued herself to the doors of the Department for Transport, and blew an airhorn to interrupt a speech by Geoff Hoon.
"[26][27] Plane Stupid claimed[28] that the action was in protest at the frequent meetings between BAA's Roland Rudd and Mandelson and other ministers ahead of Labour's approval of a third runway.
[citation needed] Lord Mandelson responded that "Whilst I'm prepared to take my fair share of the green revolution on to my shoulders, I'm less keen on having it on my face", and John Prescott said that "What is totally unacceptable is the way the woman walked away claiming it was her right in democracy.
[34] In the Guardian ahead of the G-20 protests, Deen argued that the green movement is strong as it relies on networks, built through baking cakes and making bunting rather than on violence and confronting police lines.