Walsall Security Printers deals with many stamp and security priting jobs. Inlcuding many stamp related runs such as first day cover stamp / envelope printing.
First day covers began as a method of collecting memorable stamps. a Philatelist would buy the stamp on the day it was printed and mail it so that it also bears the postmark to indicate it was posted on that first day. Many companies now create and print elaborate envelopes which are sold as first day covers often in presentation packs or gift sets.