Kelsey was apparently a neighbour of Maria on or near Bannerman Road, as she approached the Jacksons because she noticed the moving vans in 2008. Almost immediately after meeting Maria, she suggested they go into town on the free Bubble Shock! bus. The ride was only free, however, because it made a mandatory stop at the Bubble Shock! factory. She and Maria got embroiled in the mysterious happenings there, and soon met the Archetype, who would later come to be known as Luke Smith. She was briefly held prisoner by Mrs Wormwood and used for her knowledge of Sarah Jane Smith.
Although she thrust her way into Sarah Jane's attic, and met K9, she was not involved with the final remedy to the Bane crisis, as she was under the influence of the Bane chemical.
She was later described by Maria as "backtracking like mad — saying there's no such thing as aliens". (TV: Invasion of the Bane)
The character was only named "Kelsey" in the credits, but addressed on-screen as "Kelsey Hooper."
The decision was made for the character not to return after the pilot episode. Her role in the story was fulfilled by Clyde Langer in further series. It is speculated that it was because the character was not popular and/or that she was a pain to work with on set. No explanation was made by the BBC.