The New South Wales Diadem Issue will be represented by the only recorded unused 8d multiple, at the recently announced Collectors Series auction, which will take place on January 23 in London.

The vertical pair will be sold with a £12,000-15,000 ($19,186-23,975) estimate, as one of the most highly valued lots of the sale.

The Diadem Issue replaced New South Wales' previous stamps, which were beset with problems after they were paper watermarked with the denomination

The usage of stamps in New South Wales - a former British colony in Australia - was first introduced following a reform of its existing postal service in 1848. The first locally produced stamps were issued in 1850, and have now become known as the Sydney Views, due to their depiction of the famous Sydney Harbour.

Following the introduction of stamps with a Queen Victoria design in 1851, the Diadem Issue followed in 1854, with locally produced 6d and one shilling stamps issued, printed from plates engraved by Perkins Bacon - printer of the Penny Black.

The issue takes its name from the portrait of Queen Victoria wearing a diadem crown. It is unusual to find examples from this issue where the margins do not cut into the design.

The pair at auction have mainly good to large margins, except at the upper right where the margin just cuts into the central vignette. Both stamps have a dull yellow-orange colouration, just one of many varieties found in this issue.

With part original gum and a strong impression, these will undoubtedly attract the attention of British Commonwealth collectors. The auction house describes the lot as "one of the most outstanding pieces of the entire Diadem issue."

Paul Fraser Collectibles has a selection of the finest Great Britain and Commonwealth stamps for sale, including our latest addition, a mint block of 12 Penny Black stamps from plate 3, which is believed to be the largest surviving multiple from the rare plate in private hands.