These spectacularly carved brackets in the full rococo taste are virtually identical to a design by Mathias Lock and H. Copland published in their 1752 publication of A New Book of Ornaments, pl. 12, and reproduced here (see E. White, Pictorial Dictionary of British 18th Century Furniture Design, Woodbridge, 1990, p. 399).
A masterful designer and specialist carver, Lock was the first to publish carvers' ornament in the new French rococo taste in pattern books such as Six Sconces published in 1744, Six Tables (1746) and A Book of Ornaments (1747). Lock earned enormous respect from his colleagues who at the time of his death described him as 'the best Draftsman in that way that had ever been in England'.
Matthias Lock's career as 'Carver' is printed on his trade card dating to around 1752 when he was working at Tottenham Court Road, and according to a diary of that year, he was employed as carver by Lord Northumberland, Lord Holderness, and a Mr. Bradshaw. Following the publication of A New Book of Ornaments, he is thought to have established a relationship with Thomas Chippendale, providing piece-work carving and collaborating in Chippendale's enormously successful pattern book which he first advertised in 1753 as The Gentleman and Cabinet-Maker's Director; Being a New Book of Designs for Household Furniture in the Gothic, Chinese and Modern Taste, as improved by the politest and most able Artists.
A pair of matching brackets, almost certainly made en suite was with Vernay and Jussel in New York from 1978-1984, having been with dealers Asprey in London, and J. J. Wolff in New York. A further pair of brackets in a similarly rococo taste are shown in situ in the Library at Hackwood Park, Hampshire, in H.A. Tipping, In English Homes, period IV, vol. I, p. 241, pl. 309.
For a full account of the work of Lock and Copland see M. Heckscher, 'Lock and Copland: A Catalogue of the Engraved Ornament', Furniture History, 1979, pp. 1-23, pls. 1-67B.