The arms are those of William (Lowther), 1st Earl of Lonsdale, 2nd creation, and Viscount and Baron Lowther of Whitehaven (1757-1844). He was created a Knight of the Garter in 1807.
The Earl of Lonsdale was known to be a profligate spender. Robert Smirke wrote of him in the Farington Diary: "His income is supposed to be from 80 to /P100,000 a year, but He has vast expences [sic]. He has 4 establishments, one at Lowther, also at Whitehaven, Cottesmere in Rutlandshire, and in London" (as quoted in The Complete Peerage). Upon his inheritance of the title in 1807, he commissioned an extensive service of plate from leading Regency silversmiths such as Paul Storr and Digby Scott & Benjamin Smith.