Mathews has contributed to many sketch shows, including Harry Enfield and Chums, The All New Alexei Sayle Show and the Ted & Ralph segments of The Fast Show.

However, it was with Father Ted (three series, 1995–1998) that he and Graham Linehan made their biggest impression. It debuted on Channel 4.[1][2][3] The writing partnership had previously co-written the comedy Paris4 (one series, 1994), also for Channel 4.

Both Linehan and Mathews worked on the first series of sketch show Big Train, but Linehan dropped out for the second series. Mathews has also contributed to other British comedies such as Brass Eye, Jam, Black Books and later Toast of London. He later contributed sketches for Kevin Eldon, including the Amish Sex Pistols.[5]

In 1999, Linehan and Mathews created the sixties-set sitcom Hippies, but the six-part series (which starred Simon Pegg and Sally Phillips) was written by Mathews alone.[6]

In late 2003, the two men were named one of the 50 funniest acts to work in television by The Observer.[7]