Stevenson takes the role of director of group marketing and UK retail banking strategy. She will be responsible for brand advertising and for growing Lloyds' retail banking business. She will report to group executive director Eric Daniels.
At Mars Stevenson held the role of European franchise director, responsible for marketing Celebrations, Milky Way and M&Ms in Europe.
Stevenson, who joins in January 2003, replaces Ford Ennals, who left in January this year. Ennals quit the role after a restructure of marketing by Daniels. Ennals is now managing director at Britannia Music Company.
In April marketing communications director Adam Tuson joined Ennals at Britannia, as marketing director.
Lloyds TSB, which is the UK's fourth-biggest bank, currently uses Rainey Kelly Campbell Roalfe/Y&R to handle its advertising.