The collection comprises of two large volumes containing details of the clients' requirements, costs and often a diagram of the flag or banner. Although shipping companies are well represented in the order books, Porter's made flags for international and national clients. Governments and organisations such as the Fiji Police and the Admiralty and companies such as Gillette and Bank of Ireland all feature in the order books.
The volumes cover the date span 1939-1998, but his includes repeat orders with previous clients, so they probably do not represent all the company's orders during these years.
The order books are alphabetically arranged by client name, but not indexed. Each client has an individual page, containing a description of the flag, often with a drawing, costs and details of repeat orders.