Brigadier Lethbridge-Stewart as played by the late Nicholas Courtney, was a stalwart of the series in the early seventies and appeared in a total of 102 episodes over the years. The actor died earlier this year after a long illness.
The 2011 series finale, The Wedding of River Song, saw the Doctor learn of the death of his former colleague in a phone call from the nursing home where the fictional brigadier spent his last days. "I'm afraid Brigadier Lethbridge-Stewart passed away a few months ago," the nurse told the Doctor. "It was very peaceful. Talked a lot about you, if that's any comfort. Always made us pour an extra brandy in case you came round one of these days."
Executive producer, Steven Moffat, said of the decision to include the tribute to Courtney's character:
In a story about the Doctor going to his death, it seemed right and proper to acknowledge one of the greatest losses Doctor Who has endured.The character of The Brigadier first appeared in 1968 as Colonel Lethbridge-Stewart, in Episode Three of the Patrick Troughton story The Web of Fear. His last appearance in Doctor Who was in the fourth episode of the 1989 story Battlefield.
After the series returned in 2005, viewers were told his character was in Peru until he was revived again for two episodes of The Sarah Jane Adventures, Enemy of the Bane
The Phone Call, BBC, via the BBC Doctor Who site - may not play outside of the United Kingdom