She was chosen by judges for her work spearheading the Gurkha campaign for settlement rights. As a figurehead she was able to move seamlessly from the media scrum to heavyweight political programmes such as the Andrew Marr Show, and had the clout to secure meetings at the highest political level.
The campaign culminated in a government u-turn, and many tipped Lumley for a subsequent career in politics. However she has said she is not interested in such a move.
Elsewhere at last night's glittering awards ceremony, held in the Grosvenor Hotel on Park Lane, Unity scooped a brace of awards, in the Live Brand Experience and Best Green categories.
In-house teams were well represented in the awards, with the National Autistic Society taking the Public Affairs gong for its Autism Bill campaign, and the Mayor of London's press office winning the Public Sector award for the Help a London Park campaign.
The Department of Health won the Corporate Communications and Publications category for its NHS 60 campaign, which celebrated 60 years of the health service.