Ben Summerskill intended to leave the post of chief executive at Stonewall last year after 10 years, but then the coalition government said it was prepared to introduce gay marriage, which eventually became available on 29 March. "It would have looked eccentric if I'd suddenly disappeared right at that moment," he says.
When he arrived at Stonewall, the charity estimated that it would take 20 years to achieve legal equality for lesbian, gay and bisexual people in Britain. It has happened in a decade, but Summerskill does not think the mission has been accomplished yet.
"There is probably another 10 to 15 years of work in this country to change public attitudes," he says. "One thing that I was always crystal clear about was that until we had legal equality in Britain we were on shaky ground parading around the world telling other people what they ought to do. It is not an authentic way of campaigning. Now that has been achieved, with the arrival of equal marriage, it is perfectly proper that Stonewall and others should be campaigning in other countries."
Given this major advance, it's perhaps surprising that it is not one of the aspects of his time at the charity of which he is most proud. Instead, he cites its finances and diversity among its 64 staff. When he left the charity in February, half of them were women; the figure was 30 per cent when he joined. The proportion of black and minority ethnic staff rose from 6 to 21 per cent; staff with disabilities increased from 5 to 16 per cent; and heterosexual staff increased from zero to 25 per cent. He says: "I am proud that we were not just telling other people that diversity matters, but were actually showing that things can be changed."
Summerskill is also pleased that he took a "financial basketcase with £11,000 of reserves" through the recession with a rising turnover. Stonewall now has an annual income of £4.33m and £3m of reserves. "It sounds very boringly technocratic and managerial, but it's important to me," he says. "It's all very nice saying we want to change the world, but if the cash flow isn't sorted then that's just an aspiration."
Stonewall has made a big impact politically. Summerskill decided to build trust among all parties, rather than forming particular allegiances, and he says this put Stonewall in a strong position. "Given in particular that we still have the House of Lords to deal with, if you are a lobbying charity you have to build cross-party consensus to get anything done," he says. "If you appear to be banner-waving lefties, then the reality is you imperil that possibility."
He says Stonewall is rather less anxious than many charities about the lobbying act because it would never spend the amounts of money that have to be accounted for under the act. He says: "We didn't go into overdrive about it because my great belief is you don't go into full-frontal offensive unless something is going to affect you - and I'm not sure it will."
Some of Stonewall's success during his tenure is due to its "ruthless focus", he says. "In the lobbying field, sometimes you have to be opportunistic, but it's also important to tell donors what you are focusing on. It is important to be candid - false expectation can lead to disappointment."
He uses the example of the Education for All campaign, launched by the charity in 2005 to tackle homophobic bullying. Summerskill insisted it should focus on secondary schools. "I got some flak because there is also homosexual bullying in primary schools and universities," he says. "But we had only three staff working in the area. You can't pretend to do everything. I wanted to move the needle in secondary schools first, because that was where the problem was worst."
From this campaign came Stonewall's uncompromising slogan "Some people are gay. Get over it". Summerskill believes its success lies in its simplicity and that it differentiates itself as a poster campaign from "all the smiley faces that litter the charity world". He adds: "I say this as a former tabloid hack - it often takes more effort to express a concept in 10 words than it does in 500. Charity people are very good at coming up with 50,000-word reports, but there is less clarity when it comes to communicating in the public space.
"Some are afraid that if we communicate in plain English, we won't look clever; I say the opposite is true. If you are brave enough to communicate in plain English, most of your stakeholders, including politicians, recognise a charity that knows how to talk to people."
For the next three months, Summerskill is "assiduously saying yes to nothing" while he "clears his brain" and enjoys the luxury of turning off his phone at night. "I feel it's someone else's turn to do Newsnight and the Today programme," he says.
2003: Chief executive, Stonewall
2000: Chief leader writer and assistant editor, The Observer
1998: Media editor, Daily Express
1995: Diarist, Evening Standard
1990: Freelance journalist