Queer

Queer was a human slur for non-heterosexuality. While sometimes used as a derogatory term, (PROSE: Damaged Goods) the term was also used by those within the LGBT+community, as somewhat of a shared identity. (PROSE: Head of State)

As a noun, "queers" could mean "deviant men". Harry Harvey, ashamed of his attraction toward David Daniels, called David "queer filth", and told him to go back to "[his] kind", that he might "infect [him]". (PROSE: Damaged Goods)

When Paul Magrs' grandmother died in 1996, Paul's father, who hadn't spoken to Paul in years, got in contact with Paul over the phone. After Paul refused to go to the funeral, Paul's father called Paul heartless, as Paul was "a queer" and he "hadn't grown up right". (PROSE: The Story of Fester Cat)

In 2009, Clement McDonald called Ianto Jones a queer, saying that he "could smell it." Ianto objected, implying through the phrase, "This isn't 1965" that the word was old-fashioned and no longer appropriate in the 21st century. (TV: Children of Earth: Day Three)

In the 21st century, Rachel Edwards, herself a bisexual, used the adjective queer, wondering how Lola Denison was with "queer stuff", to refer to issues regarding the community. (PROSE: Head of State)

Some gay men, such as Iris Wildthyme's companion Tom, also considered themselves queer. (AUDIO: Wildthyme at Large, PROSE: The Haberdasher's Tale)

The young film actor James "Jimmy" Reynolds was "queer as a dog's hind leg," according to Edmund Trevithick, which prompted the nickname "Debbie Reynolds". (PROSE: Nightshade)

Behind the scenes
Queer is a reclaimed term which functions as an umbrella for various sexual and gender minorities. For context on Ianto's comment, its use as a derogatory term was indeed at its height in the 1960s, before those in the community reappropriated the word queer in the late eighties, as a mark of pride.