Great Britain 1987 31p Europa, British Architects error, SG1357a Saint Kitts-Nevis stamps known affectionately as "the double

known affectionately as "the double heads"

and perforations 14x13½ (top four rows) and 14x14½ (bottom six rows) se-tenant

being one of only two plate blocks possible

The text below reads in full:

Great Britain 1987 31p Europa, British Architects error, SG1357a Saint Kitts-Nevis stamps known affectionately as "the doubleGreat Britain 1987 31p Europa "Stuttgart Staatsgalerie" British Architects, SG1357a A superb unmounted mint, with full original gum, example of the rare partially perforated error, presented as a bottom left hand corner marginal cylinder block of sixteen. This remarkable piece contains: One completely imperforate horizontal pair (lower left), Seven partially perforated stamps, and Seven normally perforated stamps. A visually striking and significant