Mangan has cited the artist Georges Seurat as one of his major influences. Like Seurat's Mangan's style is very methodical rather than a natural or impressionist representation. There is a wonderful geometry in Mangan's paintings provided by the careful position of figures, but also by the repetition of shapes and patterns. The stillness and silence in Mangan's paintings are characteristic of his work and nowhere is this more apparent than in the harbour scenes where the glassiness of the water and lack of movement, in a normally busy place, is rather ghostly. The artist's use of chiaroscuro "Light/Shade" as a technique also emphasises this atmospheric feeling. A technique first employed by Italian old masters such as Caravaggio and so often used too in the 20th century by directors in film noir movies of the 1940s and 1950s.