1981 set of four individual local stamps from Steep Holm, depicting different butterflies: the red admiral (14p), tortoiseshell (20p), peacock (30p), and painted lady (44p).
U/M / Unmounted Mint / MNH / Mint Never Hinged (invisible gum).
About Steep Holm
Steep Holm is a small (1 km long) and now-uninhabited island in the Bristol Channel, close to Weston-super-Mare and forming part of North Somerset.
Since 1976, the island has been owned by the Kenneth Allsop Memorial Trust, a registered charity created in memory of the naturalist and broadcaster Kenneth Allsop, and with the aim "to protect, preserve and enhance for the benefit of the public the landscape, antiquities, flora, fauna, natural beauty, and scientific interest of the island of Steep Holm in North Somerset, and to advance the education of the public in the natural sciences."
During the summer months, the Trust organises official (and tide-dependent) boat trips to the island from Knightstone Harbour in Weston-super-Mare, which is the only legitimate way to visit Steep Holm.
Once there, the island's visitor centre sells Steep Holm local stamps, which can be used, alongside a Royal Mail stamp for onward transit, on mail posted in the island's postbox. The first set of Steep Holm stamps for such use is believed to have been issued in 1980, and further issues have continued to be produced until at least 2012.