Easdale is one of the Slate Islands, in the Firth of Lorn, Scotland.  The island nearly closed in the 1960s when the population dwindled to only 7 people.  However the island has seen a dramatic regeneration in the last few years and the population is now around 60 full time residents.  From the island's visitor's web site is this posting:

These stamps CANNOT be used as a postage stamp, as Easdale Island is part of the United Kingdom, and therefore our postal service is provided by The Royal Mail. These "stamps" (or labels as they should be called) may have collectors value, but they are certainly not used for postage on this island.  If you wish to use these labels then they HAVE to be accompanied by a recognised official postage stamp.