Lesbian, gay, bisexual and queer (LGBQ) women living in the United Kingdom (UK) experience worse health than their heterosexual peers throughout their lives, but less is known about health inequalities in older age. This study uses population-level data to examine inequalities among LGBQ older women and women who prefer not to disclose their sexuality, compared to heterosexual women. Analyses use data from women aged 50 and older who were active in Waves 3 and 7 of the UK Household Longitudinal Study (also known as Understanding Society) (N = 8,209) to examine inequalities in socio-economic conditions, health and alcohol consumption across sexual orientation groups. LGBQ older women are on average younger and have higher socio-economic resources than their heterosexual peers. In contrast, women who prefer not to disclose their sexual orientation are older and have the lowest income and educational qualifications. Results of the health inequalities analyses show that LGBQ older women are almost twice as likely as heterosexual older women to engage in harmful alcohol consumption. Older women who prefer not to disclose their sexuality have worse physical and mental health than heterosexual older women. The health of LGBQ older women and women who prefer not to disclose their sexual orientation is one of the most neglected research areas in UK gerontology. Findings of this study contribute to our understanding of their social and health circumstances, and illuminate methodological limitations in existing data.