Odd 11d value from the 1962 Anti Malaria set of three.
U/M / Unmounted Mint / MNH / Mint Never Hinged.
About Herm Island
Herm Island, which is one of the smaller Channel Islands, and within the Bailiwick of Guernsey, produced its own stamps between 1949 and 1969.
Unlike many of the labels that appear to come from islands off the coast of the UK, those of Herm performed a genuine local postal function. Mail posted on the island, which did not have an official British post office, carried a Herm Island stamp for transport to the Guernsey mainland, and a UK stamp for the journey beyond. One publicity document, issued by Herm's tenant in 1962. reports that 150,000 pieces of mail were handled the previous year.
However, when Guernsey took over its own postal service in 1969, Herm was no longer allowed to issue and use its own stamps.