Great Britain, Scott #MH102 (Stanley Gibbons #X955)(Complete Machin Stamp Catalog #NE91)(Deegam 180.2.1)(Michel #1003C)(Yvert and Tellier #1141), used(o), 1984, Machin: Queen Elizabeth II, 18 pence, Scott (olive green), Stanley Gibbons (dark olive green), Deegam (gray green), Harrison photogravure, issued: August 28th, 1984, sheet stamp, perforations: 14¾x14¼ on four sides, all phosphorus paper (bright under the UV lamp), Deegam head type B2 (necklace pearl space clear and distinct, 6th photogravure dot at bottom left is present); Deegam value type T4 (narrow 8 [4.40x3.15 mm], small distance between 1 and 8), Scott 2025 catalog value: 50¢, slightly off-centered (very fine), which is good for the issue as most are considerably off-centered, light, black-inked, horizontal duplex cancel, from left to right, a large font message cancel on left quarter of the stamp leading to a space, then a series of parallel straight line cancel on right quarter of the stamp, the lightness of the cancel and its left-right orientation leaves the main image largely clear, sound back, good perforations; reasonable centering and largely image clear cancel warrants a selling price premium. This is not a 'bait-and-switch;' the stamp you see will be the one you receive.
Please review my terms of sale. If you are not ordering from the United States, there is a $US1.70 additional postage expense that needs to be added to the price of the stamp. If you are ordering from the United States, there is only a $US0.78 added postage expense. Also, if you make additional purchases from my offerings, they can all go in one mailing at no extra shipping expense for the added purchases. I will send the purchase by US first class mail, since the relatively low value of the stamp does not warrant signature or tracking mail. Hence the buyer assumes risk of loss or non-delivery. I will keep a scan of my mailing to verify that the correct mailing address was used.  If not satisfied, return the stamp to me at your own expense, and I will refund the cost, but not my postage to you.  If the stamp is not as described, I will refund the cost and reimburse you for postage both ways.
By way of reference, I am an American Philatelic Society member (195176) and an American Stamp Dealers Association (ASDA) member. Thank you for looking, and I hope this is the perfect stamp to fill that gap in your collection.