An early career with Odeon cinemas was interrupted by the Second World War. Cave was initially inclined to register as a conscientious objector, but revelations about the horrors of the Third Reich changed his mind, "I was basically a pacifist, but I thought the Nazi persecution of the Jews made it a just war."
Cave joined the Royal Army Ordnance Corps, in 1941, aged 20. "Homosexual soldiers were more or less accepted," he said. "There was never any disciplinary action taken against them." Despite gossip that he was a "nancy boy", Cave said the worst prejudice he ever experienced in the Army was being chided for "holding a broom like a woman".
Instead of fighting the Nazis, as he expected, Cave was posted to the Far East. During the fall of Singapore in 1942, he was captured by the Japanese. Marched north in a prisoner-of-war labour detachment, his unit was put to work on the Thai- Burma railway, 10 miles beyond the bridge on the River Kwai. Three-quarters of Cave's comrades in H force perished. He was lucky. After he suffered a bad bout of malaria, the Japanese declared him unproductive and ordered his incarceration in Changi Prison, Singapore.
It was in Changi that Cave began to accept his homosexuality. A British army medical officer gave him a copy of Havelock Ellis's "enlightened, eye-opening" 1920 book Sexual Inversion. It made him feel "much better about being gay".
Changi was, nevertheless, a nightmare of physical deprivation. When liberated in 1945, he was near death from malnutrition, down from 12 stone to less than eight. "If the war had gone on another month," he said, "I don't think I would have survived."
After risking his life to defend what Winston Churchill called the "freedom- loving nations", Cave returned to a country where freedom was still denied to gay people. Not only were homosexual relationships illegal, homophobic discrimination was rife. In 1954, Cave was dismissed as manager of the Majestic Cinema in Wembley after it was discovered he was gay. "They asked me to resign," recalled Cave. "I refused, so they sacked me."
Fortunately, that same year, Cave met the man who became his life partner, Bernard Williams, an RAF veteran and schoolteacher. At the time, Williams was married. As with many gay men then, the marriage was an attempt to overcome his homosexuality. But the wedding "cure" did not work. Williams's wife, June, realised this. She encouraged the relationship with Cave. All three became lifelong friends and ended up living together in a Bloomsbury- style domestic arrangement in Golders Green. Cave and Williams remained side by side as lovers and gay rights champions for 40 years, until Williams's death in 1994.
In 1971, Cave joined the Unitarian Church, attracted to its ideals of freedom, peace and tolerance. He played a key role in securing - during the early 1970s - the ordination of lesbians and gay men, the blessing of same-sex relationships, and the Church's advocacy of homosexual human rights.
When the information and advice service Gay Switchboard was launched in 1974, Cave was one of the original committee members. The first daily helpline run by and for gay people, Switchboard was (and still is) a vital support for lesbians and gays suffering isolation and victimisation. Cave remained a volunteer - answering the phone lines - right up until his death.
Working for Switchboard made Cave aware that bereaved gay partners are often left to grieve alone, without support from their family, and are refused legal recognition as next-of-kin (which can result in eviction from what was their joint home, denial of inheritance, and exclusion from their lover's funeral). To tackle these problems, he set up the Lesbian and Gay Bereavement Project in 1980. As well as counselling the bereaved and giving legal advice, the project successfully encouraged many same- sex couples to make wills to ensure that their relationship and wishes are recognised when they die.
Cave was proud that the Bereavement Project was the first organisation with the word gay in its title to win charitable status. That victory did not come easily. The Charity Commissioners initially demanded that it drop the "offensive" word gay from its title.
From the early 1980s onwards, Cave turned his attention to "unfinished business" arising from his wartime experiences. Furious at the ban on lesbians and gays in the armed forces, he accused military chiefs of cynically enlisting homosexuals when they were needed to defeat Nazism, and then witch- hunting them as soon as the war was over. "They treated gay people like cannon-fodder," he complained.
Despite his own wartime suffering, Cave was a leading figure in the promotion of peace and reconciliation with Japan. This provoked denunciation and rejection by many former comrades. "I will never forget what the Japanese did to us, but the time has come for forgiveness," he wrote to a friend. He was involved with the Peace Temple near the River Kwai, and lectured extensively on the need for rapprochement between former adversaries.
For 20 years, Cave battled against the Royal British Legion's refusal to acknowledge that lesbian and gay people served and died in wars defending Britain. He also challenged the Legion over its opposition to the participation of gay organisations in Remembrance Day ceremonies.
He was incensed in the early 1980s when the Legion's Assistant Secretary, Gp Capt D.J. Mountford, condemned moves to promote the acceptance of gay people as an attempt to "weaken our society", and declared that homosexuals had no right to complain about being ostracised by Legion members.
One of Dudley Cave's final public acts was last November, when he was the keynote speaker at OutRage!'s Queer Remembrance Day vigil at the Cenotaph. After laying a pink triangle wreath honouring gay people who died fighting Nazism and in the concentration camps, Cave deplored the fact that gay ceremonies of remembrance are still - in the late 1990s - being condemned by the British Legion as "distasteful" and "offensive".
Dudley Scott Cave, soldier and gay rights campaigner: born London 19 February 1921; died London 19 May 1999.