1 Crown - Elizabeth II Queen Mother, Silver Proof Issue

Issued to mark the Queen Mother's 80th birthday, this was one of several commemorative programs the Isle of Man Treasury pursued aggressively through the Pobjoy Mint partnership during the late 1970s and early 1980s — a period when the island deliberately positioned itself as a source of collector-grade proof issues for the international market. The Queen Mother's birthday provided an occasion with obvious commercial appeal across Commonwealth territories.

Pobjoy struck these in multiple compositions simultaneously, which is why the KM numbering carries letter suffixes. The .925 silver version sits in the middle of that tiered release.