Robert Adam. Design of a Sedan Chair as executed for her Majesty.
Copper engraving by P.Begbie after a design by Robert Adam,  published, in London in1775. 445 x 590mm. 
Robert Adam, the formost architect of the period, designed this sedan chair for Queen Charlotte, with classical decoration including Græcian sphinxes. He chose to include the design in his Works in Architecture, a collection of elevations and views of his most famouse works, including Syon House in Middlesex. 
This must surely  be the largest engraving of a sedan chair.
£750