This modest-looking set of 6 x 40g Worldwide, which cost £9.90 last month, sold for £361.50 on eBay this week-end.
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Thirteen bidders chased it up but the winning bid was sniped 2 seconds before the close. The first under-bidder had made a few bids and probably thought that bidding 10 seconds away would win it, but he was beaten by £10.
The stamps were rare because only one roll of 1500 was used, in the last week of January. Some were probably bought by non-collecting PO users. Those bought for collectors would be in sets of 6 designs, either all with the 40g Worldwide rate, or one for each of the possible rates:
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A set of these sold at the same time on eBay for £78.54. Seven bidders fought for this one.
The high price for the Worldwide 40g set comes about because when this particular set was issued the machines only dispensed 5 values: many collectors obtained the set of 30. Stanley Gibbons' catalogue assigned a number to each possible value (rather than each design). Now that the machines have been upgraded to provide the additional value 'Worldwide 40g' a new catalogue number must be assigned, and collectors will want this.
Nobody knows how many of either set were produced but some will have been bought by collectors in small numbers, and others will have bought multiples for sale. But there will be very few.