Abstract: An emulsion comprising an organic discontinuous phase which is distributed throughout a continuous aqueous phase, wherein the organic phase comprises a light sensitive active ingredient, and the emulsion is stabilised by a water soluble stabilising material in the aqueous phase, wherein the water-soluble stabilising material is a water-soluble stabilising polymer which has a plurality of hydrophilic and hydrophobic groups and is selected from partially hydrolysed polyvinyl acetate and addition copolymers formed from (i) at least one ethylenically unsaturated carboxylic acid esters and (ii) at least one ethylenically unsaturated carboxylic acid or ethylenically unsaturated carboxylic acid anhydride, and wherein the organic phase further comprises, a) an organic solvent which is a liquid at 25° C. and/or b) an organic phase stabilising material comprises hydrophobic moieties and is a material which is more soluble in the organic phase than the aqueous phase.