A leuco polymer includes a leuco monomer and an alkene. The leuco polymer has a molecular weight of at least 500 and is obtainable by polymerization of the leuco monomer and one or more alkene co-monomers. The leuco monomer consists of an alkene covalently bound to a leuco moiety and the leuco monomer has a molar extinction coefficient at a wavelength in the range 400 to 750nm of less than 1000 M.sup.1cm.sup.1. The alkene monomer(s) have a molar extinction coefficient at a wavelength in the range 400 to 750nm that is less than 100 M.sup.1cm.sup.1. Methods of making the leuco polymer, laundry care compositions comprising the leuco polymer and methods of treating textiles with such laundry care compositions.