An error block of four 1960-1967 phosphor issue 2d light red-brown stamps sold for £11,000 ($18,834) on the first day of Spink's Philatelic Collector Series auction in London.
The sale of Great Britain stamps took place on July 9, with a set of British empire issues to auction on July 10-11.
The block is imperforate on three sides and features a significant part of the original gum, along with a strong impression.
An 1840 Penny Black cover made £10,000 ($17,122).
The lot is addressed to a resident of Truro in Cornwall, UK and features the city's October 1842 circular date stamp.
Penny Black covers, particularly early examples, can achieve phenomenal sums at auction. The finest known example of a first day cover made £44,000 ($75,372) at Spink in 2010.
A strip of five se-tenant 1998 20p Diana issues also performed well, achieving an identical sum of £10,000 ($17,122).
The fully imperforate lot was offered in mint unmounted condition and is among the rarest examples of a contemporary British stamp.
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