On the night of 22-23 September 1943 Witherington arrived by parachute to a reception committee on farmland near Tendu, France and became the courier of STATIONARY circuit and supported another SOE courier called Jacqueline Nearne. In November she joined a new circuit called FREELANCE and changed her identity to Marie Jeanne Verges (codename Pauline) with the cover occupation of a cosmetic consultant which gave her a pretext for travelling great distances whilst carrying messages and liaising with other agents and members of the resistance. This involved countless train journeys during which she was frequently stopped and questioned by the SD and civil police and after being unable to find a suitable safehouse she resorted to sleeping in unheated train carriages during the winter which added to the exhaustion she was already suffering. For an agent this was a dangerous medical condition because mistakes were easily made, and their judgment became increasingly clouded.
After meeting agents and helping to coordinate the preparations for D-day her circuit organiser Maurice Southgate was suffering from exhaustion when he failed to use basic security checks which he had used many hundreds of times before and walked into a mousetrap (a blown safehouse were German forces were waiting). After Southgate was arrested by the SD his large STATIONERY circuit was transformed into two circuits – an agent named Maingard became the organiser of what was called SHIPWRIGHT, Witherington organised a circuit called WRESTLER and under their leadership engaged in coordinated sabotage to support allied forces. On the morning of 11 June 1944 her headquarters near the village of Dun-le-Poëllier was attacked by German forces which arrived in 56 lorries; 32 Maquis were killed, their weapons were destroyed, and Witherington hid in a corn field whilst under heavy fire before escaping. Witherington then cycled to Saint-Viâtre to meet another SOE agent to arrange a resupply and on 24 June three heavily laden aircraft dropped weapons and ammunition to her circuit and WRESTLER continued its attack on German forces and Witherington is noted for being the leader of 3,500 men of the Maquis. Maurice Southgate, DSO survived Buchenwald concentration camp and Pearl Witherington Cornioley died in France on 24 February 2008 at the age of 93.