Ernest, Duke of Cumberland, later King of Hanover: A Royal Georgian silver five-part mirror plateau, John Bridge, London, 1828 with earlier elements

comprising three rectangular sections and two semi-circular end sections, with galleries of chased grapevine and applied with ten heraldic shields, raised on twenty draped pilaster supports

The arms are the Royal Arms with a label for difference for Ernest, Duke of Cumberland, 5th son of George III, King of Hanover from 1837, by descent to
Ernest Augustus, Crown Prince of Hanover, 3rd Duke of Cumberland
Probably sold Crichton Brothers, London, c. 1923

posts and holes suggest originally one or more additional sections, border separating from base at ends of 2 sections, as noted regarding marks
In response to your inquiry, we are pleased to provide you with a general report of the condition of the property described above. Since we are not professional conservators or restorers, we urge you to consult with a restorer or conservator of your choice who will be better able to provide a detailed, professional report. Prospective buyers should inspect each lot to satisfy themselves as to condition and must understand that any statement made by Sotheby's is merely a subjective qualified opinion.
NOTWITHSTANDING THIS REPORT OR ANY DISCUSSIONS CONCERNING CONDITION OF A LOT, ALL LOTS ARE OFFERED AND SOLD "AS IS" IN ACCORDANCE WITH THE CONDITIONS OF SALE PRINTED IN THE CATALOGUE.

The composite nature of this plateau reflects the evolving status - and finances - of its owner.  Prince Ernest, having distinguished himself in the Napoleonic Wars, was created Duke of Cumberland in 1799, with an annual income of £12,000 and apartments at St. James' Palace.  Over the following decade, with the help of Rundell's, he would acquire a collection of plate worthy of this gilded era and the brother of the Prince of Wales.

By the time of the additions marked by Philip Rundell (thus between 1819 and 1823) the Duke had become highly unpopular in England, and with his wife Frederika of Mecklenburg-Streilitz was living abroad, mostly in Berlin.  After the death in 1818 of Queen Charlotte (who refused to receive the new Duchess) they visited more often, and were presumably in London for his brother's coronation in 1820.

In 1825, the Duke requested an additional £6000 per annum addition to his income, ostensibly to educate his son; Parliament had pointedly refused to increase his income after his marriage.  In the summer of 1828 the Duke of Cumberland stayed for several months in England, mainly at Windsor with George IV, and it was probably at this time that the final elements of the plateau were added.  The Duke returned to England in February of 1829 to oppose the Roman Catholic Relief Bill and remained  - a vilified figure - until he accedeed to the throne of Hanover on the death of William IV.