Tom Walker Catalogue on "Shells on Stamps" attempts to llustrate every stamp issued up to the end of 2007 which shows shells or other molluscs on postage stamps. This compilation contains over 5080 stamps and highlights 1500 details. Magnified images of many stamps are included to highlight the particular mollusc that is present.

Philippe took over the collection 4 years ago. He decided to limit the collection up to the year 2000. A big work of re-cataloguing all the “shells on stamps” in the collection was started. By combining the Tom Walker Catalog, Stanley Gibbons, Carel Touw Catalog and stamps discovered during the many collection purchases of Poppe stamps, he could define the current status of the collection and map out the direction he wanted to go with it.

Philippe & Guido Poppe are both stamp collectors specialised in subjects (either animals from before 1945 and worldwide butterflies of the family Papilionidae). Guido is an expert on shells and has written many books on the subject. Philippe got a background in web-technology and together they run https://www.conchology.be/?t=1, the leading site on mollusks with tens of thousands of visitors a day from where also the experience in mail-order business.