Universities have been accused of not doing enough to support gay and lesbian staff, despite two institutions appearing in a list of the UK's 100 most gay-friendly employers.
For the past two years, higher education institutions have been absent from the annual list compiled by Stonewall, the gay rights charity.
Despite the improvement, David Shields, director of workplace programmes at Stonewall, said a recent report by the Equality Challenge Unit suggests that the academy is suffering from a "lack of focus on sexual orientation compared with other diversity strands".
"It is important that universities address this if they are to attract and retain the best students and staff and maximise the contribution of all their people," he said. "Truly world-class organisations appreciate this, and universities run the risk of falling behind."
Imperial's inclusion in Stonewall's list, which was published this week, follows its formation of a lesbian, gay, bisexual and transgender staff networking group, known as Imperial 600, which has established a formal mentoring programme for staff. The group hosts monthly social events and monitors all college policies to ensure their language is "inclusive of same-sex relationships".
Robert Millwood, its founder, said: "By being an openly gay mentor, I hope to help other Imperial staff to come forward and provide role models for the students."
Sir Keith O'Nions, acting rector of Imperial, said that making it into the Stonewall ranking was a "milestone" for the university, adding: "Any organisation not focused on making sure it is a comfortable and non-hostile place for everyone working within it is failing in its duty."
Meriel Box, head of staff development at Liverpool John Moores, said: "The key to our success is the support of senior management, robust policies and established equality staff networks.
"Diversity is respected, valued and celebrated."