It looks like Stanley and Leslie were Joseph's cousins, not his brothers. They seem to be the sons of Frederick George BAKER and Bertha (nee CULLEN). Stanley is with his parents in Margate in 1901 (RG13; Piece: 821; Folio: 79; Page: 41).In 1911 they are with Bertha's parents, Benjamin Thomas CULLEN and Eliza in Canterbury (RG14; Piece: 4331; Schedule Number: 97). Frederick George and Bertha are in Kensington, London, with newish daughter, Hilda Muriel (RG14; Piece: 147; Schedule Number: 79)

Hope this helps