After part four of "Revelation of the Daleks" in late January 1986, fans were surprised by the broadcast of two black and white Troughton serials ("The Mind Robber" and "The Krotons"), screened by the ABC for the first time since 1971. Nearly all Pertwee episodes that only existed in black and white were also screened along with the rest of the Pertwee era in 1986, though again with the exception of part one of "Invasion of the Dinosaurs". (A full run of all available black and white serials didn't happen until the ABC celebrated the show's 40th anniversary in 2003, though at that time some Dalek stories were omitted due to an ongoing dispute between the BBC and Terry Nation's estate).