The character of Valerie Kay may be based on Vera Atkins (1908-2000), who managed the women operatives for the SOE. After the war, she dedicated herself to investigating the fate of the 118 SOE agents who went missing in France. She was successful in all but one case. Vera Atkins - Her Story
This was standard protocol for SOE operatives:
Name Codename Cover Name Circuit
Noor Inyat Khan Madeleine Jeanne-Marie Renier Cinema-Phono
Violette Szabo Louise Corinne Reine Leroy Salesman II
It was Vera’s job to look meticulously through pockets, checking labels, laundry tags, examining every article of equipment and clothing for any telltale signs that these people had come from England. Then she completed their disguises with a packet of French cigarettes, a recent French newspaper or perhaps photographs of a ‘relative’ to go in a pocket or a bag.
from Life in Secrets – The Story of Vera Atkins and the Lost Agents of the SOE by Sarah Helm