The distinctive mosaics along the second-floor level of the 1898 Hanover House building were installed to advertise an early tenant, Dr. Antonio Salviati, who designed and manufactured mosaics. He was one of the principals responsible for the rebirth of Venetian glass after its nadir under the Austrian rule of Venice, and had British partners and a London shop. Amongst his better known works was the restoration of the mosaics in the Basilica San Marco in Venice, and the mosaics on the Albert Memorial in Hyde Park, London. Salviati also worked on some of the mosaics for St. Paul's Cathedral, London. In the world of vitreous mosaics he is one of the key players, and so the mosaics on Regent House are both nationally and internationally significant.

The designs on the façade were restored in 1999, and show (from l. to r.): the arms of the City of London (white shield with a red cross and a red sword in the top-left corner), a British Royal Lion holding the Royal Arms of the United Kingdom, the arms of the City of Westminster (blue shield with a gold portcullis). By the way, Westminster is the second of the three cities that make up the heart of London, along with the Cities of London and Southwark.

The right-hand side shows a coat-of-arms I can't identify from the photo, the Lion of St. Mark over the Doge's cap, symbols of Venice, and finally the arms of the Island of Murano. Murano was and is where the Venetian glass industry is based (the glassmakers were forced to move their facilities to the island several hundred years ago to reduce the risk of fire in the city). The cities listed at the top were where the Compagni Salviati had shops. [Thanks to Graham for the research!]