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 750 nm of less than 1000 M−1cm−1. The alkene monomer(s) have a molar extinction coefficient at a wavelength in the range 400 to 750 nm that is less than 100 M−1cm−1. Methods of making the leuco polymer, laundry care compositions comprising the leuco polymer and methods of treating textiles with such laundry care compositions.