Another bell for British gay equality is ringing out across the world . The UK is to end the ban on gay men donating blood. But read the not-so-small print, and that ringing sound becomes tinny, hollow. Only gay men who have not had sex in a decade will be able to give blood.

This proposal won't help the young woman with a rare blood type, knocked over by a car, bleeding profusely. This won't help the thousands of anaemic cancer sufferers needing a blood transfusion. This will help just one person: David Cameron.

He can now say he is making good on the coalition's promises over gay equality. But like many of their other pledges in this area – in particular, to stop persecuted gay asylum seekers being sent back to their home country and to put pressure on foreign governments to protect their gay citizens – it's all gong and no dinner.

And it affects everyone. Imagine just after reading this you receive a phone call. It's the local hospital. A member of your family has been stabbed. They tell you that there isn't enough blood locally. Would you rather your family member died or that they were given blood from a gay man who says he has never had unsafe sex?

This shortage scenario is not far-fetched. Indeed, in December, during the big freeze, fears grew that we would run out, so an appeal was issued for O-negative donors. Heterosexual donors that is.

But the effects go further. What message does a government send out when one group cannot give blood even if they have only ever had safe sex? Simple: "Gay men are not to be trusted over their sexual history." In contrast, straight men who pay for sex can give blood a year later. It would seem that the NHS will believe people who say they are heterosexual, but not those gay people who profess to only ever playing safe.

I have always used condoms. I personally know of not a single heterosexual person who has used condoms every time they have had penetrative sex. But I do know of a heterosexual who refuses to give blood because of the ban: my mother. Unaware of the exclusions, she went along to her local clinic to become a donor. When she read the forms which detail those who are not permitted, she gave the paperwork back and announced: "If my son's blood isn't good enough for you, then nor is mine."

Here's another anomaly. I am on the bone marrow register. In fact, last year the Anthony Nolan Trust contacted me because I was a potential match for a woman who needed a transplant. So, my marrow is okay but not my blood?

I would happily donate blood every 16 weeks (the minimum time between donations). I would happily donate my blood to someone that despised me for being gay if it meant saving their life. But my country won't allow me to help others.