H. W. Porter made at least 4 FDCs, three being addressed to himself and one addressed to J. B. Jackson. A FDC addressed to Porter not illustrated above is found on page 119 of H. Gobie’s book The Speedy which addresses the U.S. Special Delivery System. The book covers all special delivery issues and is recommended reading for the specialist. Porter’s name is mentioned a number of times for various reasons in Philip Ward’s column in MeKeel’s Weekly Stamp News during 1922. This appears to be Porter’s first venture in FDCs. I have seen some FDCs of other issues addressed to Porter. Unfortunately, I have not seen a 11-cent Hayes FDC (Scott 563) that can be attributed to him. There might be one out there somewhere.
Gobie, Henry M., The Speedy – A History of the Special Delivery Service, Part III, Chapter 1, Published by the Author, 1976.