This is a Royal Mail marketing initiative, introduced at the International Stamp Show 2000 with the 1990 set of Greetings stamps. The idea is that anyone can put their own chosen picture (perhaps a photograph or a logo) as a label next to a stamp (a bit like a Cinderella). This has proved a popular, personalised way to mark births, marriages and promote companies. Many different Smiler issues have followed, including Father Christmas in 2004 and Farm Animals in 2005. The name “Smilers” was chosen because they are designed to be used as celebrations of happy events.
For collectors. Royal Mail produce Generic versions of the Smiler stamps. Instead of being personalised, these versions have relevant decorative labels printed alongside the stamps instead.