The PTT's principal aims, as set out in its Deed of Trust, are to promote the principles and practice of Humanism to the public, and particularly to lesbians and gay men, and to advance the education of the public, and particularly of Humanists, about all aspects of homosexuality.
Humanism is essentially a system of thought that rejects religious beliefs and centres on humans and their values, capacities, and worth.
The PTT may also assist individuals to obtain remedies under the law where they have suffered unlawful discrimination on account of their homosexuality or their absence of religious belief.
In 1990 the PTT started publishing a quarterly magazine, the Gay and Lesbian Humanist, which featured national and international news, feature articles and reviews. Regular contributors included journalists in the UK and abroad writing for the lesbian/gay and humanist press. The magazine was widely distributed to gay, lesbian and Humanist organisations and stocked by gay and alternative bookshops in the UK.
An online successor was launched in 2008, but this year a decision was made by the Trust to give the magazine a make-over, and relaunch it as The Pink Humanist.
In 1996 the PTT started arranging secular ceremonies of love and commitment for gay and lesbian couples as the alternative to Christian "blessings" arranged – usually clandestinely – by gay clergy. The PTT ceremonies were called "affirmations". They were widely advertised, mainly in Gay Times and were soon in great demand.
A nationwide network of Humanist celebrants was established from Aberdeen in the North to the Channel Islands in the South and some donated part of their fee to the Trust. When London Mayor Ken Livingstone allowed ceremonies for gay and lesbian couples to be held at City Hall, the PTT was listed as providing them – and many of them were conducted by Denis Cobell, then President of the National Secular Society.
The provision of these ceremonies continued until the Civil Partnership legislation was introduced by the Labour Government in 2004 and it became possible for secular ceremonies to be held after registration at Registry Offices up and down the country.
For many years the PTT provided substantial indirect funding for the Gay and Lesbian Humanist Association (GALHA) when its magazine was issued free to GALHA members. It also funded the printing cost of the GALHA newsletter which was later published in place of the magazine.
It has provided funding for other LGBT and Humanist projects such as LGBT History Month, a convention of the Nigerian Humanist Movement and the Uganda Humanist Schools Trust (UK).
In July 2015 the Pink Triangle gained a new patron, Sophie in’t Veldt MEP, who was awarded the Irwin Prize for Secularist of the Year at a ceremony hosted by the National Secular Society in 2011.
The PTT is a member of the International Humanist & Ethical Union, the UK Consortium of Lesbian, Gay, Bisexual and Transgendered Voluntary and Community Organisations, the UK Cutting Edge Consortium, the Alliance for a Secular Europe. It is a supporter of the Secular Europe Campaign, Galop (London's leading anti-LGBT hate crime charity) and the Nigerian Humanist Movement.