Walsh trained in animation at West Surrey College of Art and Design, where his graduation film "Oozat" (1993), using pixelation and mask animation, was broadcast on Channel 4 and won awards at the Cork International Film Festival and the Hiroshima Animation Festival.
He devised, directed, and voiced the two series of Angry Kid animated short films, which were commissioned by the BBC, produced at Aardman Animations, and won awards including Best Animated Short at the World Comedy Short Film Festiv