Great Britain 1848-61 1d Red brown PIate 116 (Archer trial perforation), SG16b.
A fine used vertical pair of this trial perforation lettered RF-SF with neat London City ""13"" numeral cancellations. RF with torn perforations at right. Despite this obvious condition issue, this pair is of the highest rarity as these are believed to be the only recorded examples of these trials from this printing plate.
Accompanied with a 2009 British Philatelic Association certificate of authenticity.