Mat Irvine is a Technical Consultant and Visual Effects Designer who worked on television, primarily for the BBC, from the 1970s to the 1990s. As a Technical Consultant, Irvine worked on shows such as The Sky at Night, Tomorrow's World and, most recently, Robot Wars, on which he was hired as a technical consultant in 1998. As a Visual Effects Designer, Irvine worked on shows such as Rentaghost, Terry and June, Blake's 7, The Tripods, Edge of Darkness and To the Manor Born. He is perhaps best known for his work on Doctor Who, for which he was a Visual Effects Designer, from the 1970s to the 1980s. He is credited with building the first K-9 prop for the serial The Invisible Enemy. He was not told that it would be required beyond that story, thus the prop he designed was only capable of traversing the studio floor and proved useless when brought on location for subsequent stories. Irvine eventually built a second K-9 that could cover rougher ground. He occasionally operated the K-9 prop during filming. In the late 1970s and early 1980s, he made regular appearances in the BBCchildren's TV shows Swap Shop and Saturday Superstore, initially to discuss special effects on BBC drama series, and later as a more general expert on science and space issues. His connection with K-9 has continued. In 1981, Irvine served as Visual Effects Designer for the Doctor Who spin-off K-9 and Company. In 1993, he operated K-9 for the Doctor Who charity special Dimensions in Time. In 1999, he once again operated the robotic dog when a model K-9 was given to the character Vince as a birthday present in Queer as Folk. He operated K-9 in an episode of Totally Doctor Who in 2006. He spoke about his work on Blake's 7 and The Tripods in 2006 on BBC Four'sThe Cult of... series, in the episodes The Cult of...Blake's 7 and The Cult of...The Tripods. Nowadays, he makes appearances at sci-fi and Doctor Who conventions, often alongside K-9. He appeared alongside K-9 and Elisabeth Sladen on Totally Doctor Who in July 2006.