Thank you very much for your help. I can now dismiss Islington as a place of death for Thomas and Ellen. I did look at the image on Deceasedonline and the address for Thomas when he died is 32 Sonning Street, Islington and that is not an address that any of the Claytons that I know of lived at.
Thomas was still alive in 1891, he is on the census with his wife, Ellen and some of their children.
Thomas Clayton 71 tailor born Knaresborough Yorkshire
Ellen Clayton 56 dressmaker born Bath Somerset (probably more like 58 she was born 1832)
Isabel Edith Clayton 19, domestic servant born 17 May 1871
William H Marchant, grandson, son of Isabel E Clayton aged 1, born c 1890
Elizabeth Ann Parker 17 (nee Clayton) born 17 July 1873 wife of George
George Parker, 22, druggist/chemist warehouseman, born Marylebone, London 1868/1869
Francis C Gibson 13, grandson, born 1878 (Charles Frank Clayton born Chelsea 1878)
Living at 43/45 Charlotte Street, St Pancras, London
I can only think that after they all left (Elizabeth Ann and George emigrated in 1892/1893 and Francis Gibson went to Lancashire to live with his aunt. Isabel Edith Clayton married and moved away) Thomas and Ellen moved also, perhaps nearer family. The only family that they had was a sister of Ellen's living in Battersea (Matilda Clarke) and children and grandchildren in Accrington/Haslingden, Lancashire. This is why I can't find them after the 1891 census and the second Thomas and Ellen Clayton living in Islington (Campbell Road) have maded it more confusing. I will try Battersea area and Lancashire from 1891 to 1900 (neither appear in the 1901 census).