Collateral material is a term that stamp collectors use to refer to nonstamp items that help tell the stories that are depicted on stamps. This folder was produced in 1982 by the Stamp Collecting Promotion Council of Great Britain. It relates the British Theater commemorative issue of that year to the 250th anniversary of the founding of the Royal Opera House in the Covent Garden area of London. Collateral material such as this adds interest and individuality to a collection. Click here for a larger image.
Collateral material adds interest to collections, album pages and exhibits.
It complements and expands stamp themes, and it can engage people who are not stamp collectors. In this age of maximization of revenue, postal administrations offer collateral material such as first-day covers, presentation packs, books and even audio CDs. However, other people and organizations offer collateral items as well, and sometimes these are more interesting and unusual. One such item is shown in Figure 1. The front cover shows the Royal Opera House, a theater that dates to 1732.