Great Britain 1961 10 Shillings Postage Due Inverted Watermark Block of Four

United Kingdom · 1961 · 10 Shillings

This block of four 10 Shillings postage due stamps from Great Britain features the standard blue design with 'TO PAY' and 'TEN SHILLINGS'. The significance of this block lies in its inverted watermark, a known printing variety.

Postage due stamps were issued to indicate that insufficient postage had been paid on an item of mail, requiring the recipient to pay the outstanding amount. Varieties like inverted watermarks are sought after by collectors as examples of printing anomalies.