The decision about personal items was informed by what was known about what German intelligence was likely to look for. An officer traveling with official documents would normally carry personal items. A body that arrived with nothing but the official briefcase would be suspicious. A body that arrived with a reasonable collection of personal effects, suggesting a real person’s ordinary life, would be less so.
The production of these items was itself a logistical operation. Each item had to be sourced through channels that would not leave an obvious paper trail suggesting it had been assembled for a deception operation. Some items, like the theater ticket stubs and the photo of “Pam,” were obtained through means that required a certain ingenuity on the part of the people running the operation.
The backstory for Martin had to be detailed enough to withstand questions but not so elaborately specific that it could be easily disproven. The decision was made that he had spent the war mostly in England, had been involved in planning for Combined Operations, and was only recently in a role that involved travel with sensitive documents. This meant that anyone attempting to verify his service history would be looking at wartime records that were not publicly accessible, which gave the planners considerable flexibility.
The cover story for his death was a plane crash. The standard procedure for the movement of important documents across the Mediterranean was by air, and aircraft did occasionally go down over the sea. A body recovered from the sea with documents attached to a briefcase by a chain, showing signs of time in the water, would be consistent with a man who had died when an aircraft ditched and had been carried by currents to the Spanish coast.