This is a superb quality and most unusual piece of Georgian silverware made by the premier silversmith Edward Wakelin. The piece consists of a flat serving plate with wooden handle (to protect the user from heat) and a removable cover that also doubles as a heat reflector. The cover has its own silver handle and slots securely in to the back of the tray. There is a ledge towards the base of the cover that would have held a metal grill upon which the bread sat. The toaster would have been offered up towards an open fire and the combination of heat from the fire and that reflected back by the silver cover would have melted the cheese and browned the bread.
This cheese dish is of a significantly different form to most that were produced and it would seem that the clients of Edward Wakelin were particular patrons of this type of item as he seems to have produced most of the mid-18th century toasted cheese dishes. This example is of the very highest quality and bears the same engraved crest surmounted by an earl's coronet to both the tray and cover.
The underside of the base bears a very clear set of hallmarks including the maker's mark of "EW" crowned for Edward Wakelin. rthe cover is unmarked. Wakelin was apprenticed to John Le Sage and went in to partnership with George Wickes in 1747. The company begun by Wickes in 1720 was silversmith to the Royal family and in particular to Frederick, Prince of Wales who was heir to the throne, but pre-deceased his father King George II. This workshop was the birth of what went on to become Garrard & Company. It would seem that Wickes became a sleeping partner in the business in 1747 and the silversmithing side was in the hands of Edward Wakelin with all silver produced by the company bearing the "EW" maker's mark.
The crest is that of Robert D'Arcy 8th Baron Conyers and 4th Earl of Holderness (1718-1778) of Hornby Castle in Yorkshire. He was the British ambassador in Venice (1744-1746) and The Hague (1749-51) and during the 1750's was the Secretary of State for both the Southern and Northern Departments (titles later known as Foreign Secretary and Home Secretary). He had no male heirs and his titles became extinct upon his death, but was survived by his daughter Lady Amelia D'Arcy. See Wikipedia for more information.
The cover also bears the initials "F&C" surmounted by a coronet which denotes the Fauconberg & Conyers Collection. The collection was derived from the marriage of Francis Godolphin Osborne and Amelia D'Arcy and the  refers to the inventory number of the collection.