The greatest treasure of the City of London has been, until now, the least known. The unique Crystal Sceptre of c.1420 - seen only at the inauguration of the Lord Mayor and at coronations, and never photographed before - is here presented with as much as is known of its history, its materials and their origins and its first recorded outing, to the coronation of Catherine of Valois, the wife of King Henry V, in 1421 at Westminster Abbey.

Timed to coinicide with the first ever public exhibition of the Crystal Sceptre, which opens on the occasion of the 600-year anniversary of the Battle of Agincourt, this new book will present the Sceptre and over 80 of the finest and most historic pieces in the plate collection at Mansion House - the home, office and centre of entertainment for the Lord Mayor of the City of London. The regalia includes several famous items, notably the 16th-century gold and enamel Chain of Esses, the great Mace of 1735-36 and the Pearl Sword of the 1570s, carried by the Lord Mayor before the Sovereign on visits to the City. The silver-gilt and silver, used constantly during the year, includes pieces by some of the greatest names of English silversmithing - Paul de Lamerie and Paul Storr, for example - but also rare ones by more modern masters - Latino Movio and Omar Ramsden - including masterpieces previously completely unknown to silver historians.

An inscription on a silver-gilt cup presented to the Lord Mayor in 1741 records that the intention of the gift was to increas - the Honour and Grandeur - of the City of London. It is just one piece of a vast, eclectic and exceptional collection of plate, which is constantly in use at the Guildhall and Mansion House today to uphold that honour and in the grandest way possible - a rare survival of medieval practices of display. The quality and quantity of the 19th- and 20th-century pieces in particular is extraordinary.

This volume is the third in the series on the treasures of Mansion House, following The Harold Samuel Collection of Dutch and Flemish Paintings (2012) and Magnificent Marble Statutes: A Guide to the Sculpture at the Mansion House (2013). Intended to introduce to a broad audience the plate collection - as well as the history of the Lord Mayors, the City guilds and Mansion House itself, and the formation of the collection, it will also be of interest to specialists in silver, who will discover many masterpieces of style and technique.