According to a survey of 1,118 readers of Diva and Gay Times by the marketing consultancy Out Now, and reported in The Guardian, gay men in full-time jobs earn on average £34,200 a year, compared with the national average for men of £24,800. Lesbians earn £6,000 more than the national average for women.
The survey is pretty much about what gays and lesbians spend their hard earned cash on, although there is a suggestion that the latter appear to have broken through the "employment glass ceiling". I sense that the inflated wages are related to the lack of dependents more than any other factor. However, it doesn't fully explain the disparity between the pay levels of gays and lesbians. See Gay men earn £10k more than national average by Polly Curtis to make up your own mind.