The brutal murder of a young, gay man on Clapham Common is a wake-up call to those who think that, following a series of legislative reforms, gay men now live in a climate of acceptance and freedom.
In a similar way, the murder of a black teenager in Liverpool a few months ago showed that there are people so consumed with hatred that they will bury an axe in someone's head.
The optimistic view is that there is always a time-lag between changes to the legal framework and changes in public attitudes.
The pessimistic view is that changes in attitude don't necessarily follow at all, that legislation can always be reversed, and that the same battles have to be fought over and over again.
There was a harrowing article in Guardian Weekend a few weeks' ago about homophobic bullying in schools and the continuing failure of many schools to get to grips with this problem.
The infamous Section 28 has now been abolished but the article showed the limits of legislative reform in this area.
It's impossible to stop homophobic bullying without saying that it's OK to be gay. But if teachers say that they are often jumped on by parents with homophobic views, often based on religious beliefs. Some of those parents might also be school governors. Some teachers might also hold religious views that, whilst not condoning bullying, assert that homosexuality is sinful. So whilst all schools have an anti-bullying policy, there is often a refusal to acknowledge the specific nature of homophobic bullying in the way that racist bullying would be acknowledged and confronted for what it was.
In the Conservative Party now, attitudes to gay rights are widely regarded as a litmus test of modern Conservatism. I don't know why this should be so, but the fact is that no reference to modern, One Nation Conservatism is complete without using the phrase 'straight or gay', usually immediately after 'white or black'.
So it's worth noting that all the candidates in the current leadership contest, some of whom have used that mantra, have voted against some or all of recent legislation to extend gay equality.
And yes, that includes the young, thrusting, oh-so-modern David Cameron.
Liam Fox has attempted to show a compassionate side to right-wing Conservatism by focusing on the issues of mental health and domestic violence. In his conference speech he also mentioned bullying in schools. He didn't, of course, mention the problem of homophobic bullying. Hardly surprising, because he is closely aligned with the right-wing, Christian, family-values section of the party.
Sometimes when I've argued in these terms people have protested that it's perfectly possible to be against bullying while believing that homosexuality is wrong. In the same way, many Christians prattle about how much they love the sinner whilst hating the sin.
It's a position that just doesn't work in practical terms. And if you ever want to judge the validity of these kind of arguments just try substituting the word 'black' for 'gay'.
"I'm not a racist and I condemn attacks on black people but I don't think the law should treat black and white people equally."
It's a position that would only seem acceptable in the provisional wing of the BNP.
Returning to the Clapham Common murder, Peregrine Worsthorne had a letter in yesterday's Guardian saying that to avoid violence gay men would be wise to exercise discretion and not engage in what he quaintly called 'coupling' in public places.
This is a bit like saying that, whilst rape is to be deplored, women who wear short skirts are somehow inviting it.
But it's also based on some fundamental misconceptions. I have no personal knowledge of cruising in public parks. As with eating, so with sex - I'm not an al fresco kind of person. But my impression is that many men who go cruising go somewhere more private and more comfortable for the actual sex, once they've found a sexual partner.
Those who do have sex in a public place usually find somewhere out of sight of passers-by, if only because they are committing a criminal offence.
And a significant number of men who have sex in public spaces are neither self-defined nor socially-defined as gay. Remember the Labour Minister Ron Davies, married with children, who seems to have had a liking for sex with anonymous men in parks and lay-bys? It may not necessarily be a preference by such people but a necessity. When straight or bisexual men want sex with other men it has to be secret and anonymous; going to gay pubs and clubs is too dangerous an option for them.
When health professionals were first fighting the AIDS epidemic, they quickly cottoned on to this fact and used to advertise for health workers not to work with 'gay men' but to work with 'men who have sex with other men'. They realised that unless the conventional labels were dispensed with they were going to miss large numbers of men who sometimes had sex with other men.
The final riposte to Worsthorne is that casual sex in public places is not confined to gay people. In recent years the phenomenon of 'dogging' has spread like wildfire and even had a celebrity boost when famous actors and footballers have been caught at organised sex sessions in country parks late at night.
That's not a suggestion though. Not just because I abhor violence but because it could lead to some unfortunate scenarios: "Sorry, Dad, I didn't see it was you in the dark. Mum said you'd gone to the darts match."