To mark the 350th anniversary of the foundation of the Royal Observatory, Greenwich, Royal Mail have released a special commemorative issue. The miniature sheet celebrates prize-winning clockmaker John Harrison's Marine Timekeepers and comprises four stamps, all 1st class, featuring images of each of Harrison's prototypes for measuring longitude at sea which became known as H1, H2, H3 and H4.
The Gold 500 cover image is framed by a 22ct gold-blocked border and the cover bears a London SE10 handstamp. Numbered limited edition of 500.
