Horkan’s work shows a love for colour and the surface of the canvas, her work is vigorous and expressive. The subject becomes the process in many of her works and the surface a 3d space. Her work is by no means directly representational and alludes to subjects such as birds and butterflies by offering a suggestion of their forms rather than any literal or realistic transcriptions. She playfully engages with scale and perspective, making large what is typically small but her central focus is on colour, gesture and mark making. Horkan’s work has an energetic, flickering quality that is particularly evident in her underwater scenes.