Samuel Horsley was Dean of Westminster from 1793-1802 but he has no memorial in the Abbey. His grave was originally at Newington Butts in Surrey where he had been Rector 1758-93 but due to the demolition of that church for a railway line he was moved to Thorley in Hertfordshire where he served as Rector 1777-82. His portrait hangs in the Deanery.
He was the son of the Revd.John Horsley and his wife Anne (Hamilton) and was born on 15 September 1733. Educated at Cambridge he later became archdeacon of St Albans, a prebendary at St Paul's cathedral and at Gloucester cathedral, Bishop of St Davids and from 1802 Bishop of St Asaph. In 1774 he married Mary, daughter of the Revd.John Botham and his second wife was Sarah Wright. The Revd. Heneage Horsley (who married Frances Bourke) was his child by Mary. He died on 4 October 1806.
A photo of the portrait can be purchased from Westminster Abbey Library.
"High Church Prophet, Bishop Samuel Horsley..." by F.C.Mather, 1992
Oxford Dictionary of National Biography 2004