Jennings, who joined the agency yesterday (27 May) in a full-time role, will be responsible for Grass Roots' automotive strategy, as well as taking the lead on a number of new business projects. She will work across Grass Roots' offices in Marlow, Fleet and Putney.
Jennings worked at Grass Roots for five years between February 2007 and April 2012 before leaving to take on roles with Silverstone Circuit and as experiential programmes manager with Rolls-Royce Motorcars.
This follows the appointment of James Thompson, who joined Grass Roots this month.
Hannah Wilkinson, client services director for Grass Roots Meetings & Events, said: "Jane’s reputation in the business is second to none and it’s a vindication of all that we’ve been doing that she’s chosen to return to us. Automotive has always been a strong sector for Grass Roots and, on the back of recent new project wins, Jane’s return couldn’t be better timed."