This series consists of a nominal card index of SOE personnel and contacts in Belgium and certain other individuals. The index was created by the merger of a number of separate indexes, including a T Section index, a Belgian Training Section index, a Bayswater index and others. Because of the number of different indexes here combined, there are sometimes more than one card relating to one individual. Though most of the cards are typewritten, a number are in manuscript or contain manuscript additions. The index includes a very few Dutch section cards, though the reason for their inclusion in this index is not clear from the information on those cards.
The exact details recorded on each card vary according to the type of index it originated from, but typically the cards might list pseudonyms used by the subject, their contacts in the field, details of operations participated in and accounts of their activities or roles in SOE or the local resistance, contact addresses and so on. The Training Section cards typically relate to individuals considered by SOE for recruitment, and include information about their suitability or otherwise for employment, some personal details including contact addresses, date of birth and so on, and if they were not recruited, reasons for rejection.
The index also includes references to German officers based in Belgium and to known or suspected Belgian collaborators or traitors.