The Baby Farmers
Alice Guppy worked for Torchwood Cardiff in the late Victorian era. She was in a relationship with fellow Torchwood agent Emily Holroyd.
Alice Guppy was an orphan with a criminal background. (The Baby Farmers) She originally lived and worked in Scotland. Torchwood didn’t know what to do with her when they found her, so they shipped her down to Cardiff. (Risk Assessment)
The pair offered Jack Harkness a place at Torchwood on discovering that he couldn’t die and possibly knew about The Doctor. Alice found Jack attractive but avowed that she found Emily more so. She came into conflict with Jack when he witnessed her cold-bloodedly executing a blowfish alien Jack had captured on his first assignment. She was sadistic on several occasions, delighting in assaulting and torturing Jack on first meeting him. (Fragments)
Around 1899, Alice and the rest of Torchwood infiltrated and destroyed the HMS Hades after it was found to be a lab for experimenting on aliens. (The Baby Farmers)
By noticing energy signals in 1901, she discovered a version of Jack from the future, who had been buried by Gray and John Hart in 27 AD. At his request, she and Charles Gaskell placed Jack in cryogenic suspension until the 21st century so that he could avoid crossing his own timeline. (Exit Wounds)
BEHIND THE SCENES
The series 2 version of the Torchwood website showed a diary entry describing how Alice (unnamed in the text) became a member of Torchwood Three. It said that Emily, whom had previously been married, had a husband, whose situation in late 1898 was “complex”. It also depicted Alice by 1898 as living a two-day journey from Cardiff, with a stop-off at a lodging home in Bath.
After the death of one of Emily’s team, Alice, expecting a reprimand for having wounded Mrs Hailsham in the laundry room on 12 September 1898, was given a contract on the 13th to be employed as an Investigations Agent for Torchwood by the governess, and have her charges dropped by signing it.
The following day, Emily collected Alice for the trip to Cardiff. She informed her of the death of Emily’s previous partner in Torchwood, whom had succumbed to a “mutative infection”, becoming the new queen of a snake-like race. Emily was “obliged” to burn her partner to death. She also told Alice what the Torchwood Institute was about.
On the 15th, she noted her diary would become “less comprehensive” from then on, due to the sensitive information her experiences with Torchwood would entail. 
The series 2 version of the Torchwood website features a morgue stock take by Owen Harper. It lists Alice’s body as being one of the morgue’s “permanent residents” in bay 12. 
A Torchwood agent resembling Alice appears in the IDW Publishing Doctor Who comic The Time Machination.