Sotheby's announced a sale of stamps from The British Postal Museum & Archive in London on 11 July 2013. The auction will comprise material duplicate to the archive collection, with proceeds to benefit the new home of The British Postal Museum & Archive, which will be situated at Calthorpe House on London’s Mount Pleasant site and is scheduled to open in early 2016. A second sale, comprising entirely different duplicate material to the first auction, is scheduled to take place at Sotheby’s in London in February 2014.

Stamps from ‘Registration’ or ‘Imprimatur’ sheets are among the most highly prized items among stamp collectors. Only two of these special sheets were ever produced for each stamp in this sale. The BPMA is to retain the original sheet which, due to its protected status, will never be sold; Sotheby’s will present for sale elements of the duplicate Registration sheets. Sotheby's auction is a unique event, since no other examples of these items will be made available, and as such, represents a once-in-a-lifetime event for collectors.

Commenting on the collection of stamps to be offered for sale at auction, Richard Ashton, Sotheby’s Worldwide Philatelic Consultant, said: “This selection of material from The British Postal Museum & Archive includes numerous items that are of the utmost rarity. Now in my 50th year as a professional philatelist, I have never seen such an important sale of its type. Many are the only examples of their kind ever to come on to the market. Quite aside from their rarity, these extraordinary stamps are also of great beauty – engraved to the highest standard by leading masters of the day. There are magnificent sheets of the 'Seahorse' stamps of King George V, and important blocks with Registration Certificates on the reverse of the reigns of King Edward VIII and King George VI. Collectors will never again have such an opportunity to purchase such rare and beautiful items.”

Commenting on the sale, Adrian Steel, Director of the BPMA, said: “As well as offering collectors an exciting opportunity to acquire rare and important philatelic material, we are thrilled that this sale will directly support the development of the BMPA’s new home. Whereas currently our world-class collections are held in storage and therefore largely hidden from public view, the new British Postal Museum & Archive will make our collections, and the story they tell of British communication, industry and innovation, available to everyone. We hope that everybody who supports this sale will feel proud to be playing their part in restoring Britain's postal heritage to its rightful place on the national and international stage.”

The first stamps printed from an approved and finished printing plate are called ‘Imprimaturs’. Once printed these would be taken from the printers to two receiving 'officers' who would subsequently type an endorsement on the reverse of the sheets and would often pencil annotations on the front side. The resulting sheets are called ‘Registration’ sheets; they are characterised not only by the endorsements and annotations mentioned above, but also by the fact the sheets have no perforations. These magnificent signed and dated 'Registration' blocks have never previously been available to collectors. The sale will include some 50 or so complete Registration blocks, as well as stamps (‘Imprimaturs’) taken from the Registration sheets: single stamps, pairs, blocks of four, and larger blocks which contain important archival notes in the margin.

In the July sale, collectors will have a choice of selected issues from the reigns of King George V (Seahorse issues), King Edward VIII and King George VI (definitive issues). The auction comprises 191 lots and is estimated to bring in excess of £5 million. Details of these stamps will be available in due course. The second sale in February 2014 comprises entirely different material.