Lavinia once told Sarah Jane that she had invested in Brendan's education so that he would not believe everything that he read in the newspapers. He attended Wellington College but sought to convince Lavinia to allow him to attend the local comprehensive school in Moreton Harwood as he did not like boarding. He had a close friend at Wellington named Travis, whose father was in the market gardening business. Lavinia's estate also included a market garden. He was taking three extra O-Levels during the 1981-1982 academic year: Additional Maths, Physics and Biology. Having a keen interest in computer technology, he was extremely impressed by K9 and his computational abilities. Although the original K9 unit had been built by Professor Marius in the year 5000, Brendan was nevertheless familiar with many of the components used in his construction.
As Lavinia was then in the United States, he, Sarah Jane and K9 spent Christmas Day 1981 with Howard and Juno Baker, whom Sarah Jane had mistakenly believed had been part of the Hecate Cult only four days earlier. (TV: A Girl's Best Friend)
After this happened, Sarah, Brendan, Lavinia and K9 continued to investigate and stop other cults and witchcraft covens present in Britain. (PROSE: Powerstone, The Shroud of Azaroth, Hound of Hell, The Monster of Loch Crag, Horror Hotel, The Curse of Kanbo-Ala)
In the late 1980s and early 1990s, Brendan studied at the University of Cambridge. (PROSE: Housewarming) After he returned, he assisted Sarah and K9 in investigating a supposedly demonic pig spirit. When K9 became possessed by this spirit, Sarah worked out a way of exorcising it by electrocuting K9, defeating it. (PROSE: The Sow in Rut)
He was not present at Sarah Jane's aborted wedding to Peter Dalton in Ealing in 2009 and thus missed meeting the Doctor, then in his tenth incarnation; whether Sarah Jane invited him is unknown, as is his reason for not attending if he was invited. (TV: The Wedding of Sarah Jane Smith)