Why can’t I give blood?

I read about the national shortage of blood last week with a feeling of gloomy inevitability. The brains of the nation are scrambled, Westminster’s insane, of course the country’s bleeding out. But at least, I thought, I can help a bit. I’ve given blood in the past and I enjoy it. There’s the feeling of warmth and purpose, and biscuits. I’d never fork out for a packet of custard creams, but like most English women and men I’m a sucker for one or two free on a saucer in a medical setting.

Our blood donor scheme is actually all-round cheery. Each country has its own circulatory system, a flow out from the veins of donors, off to hospitals and into patients. Some countries have to resort to paying donors for blood, and the inevitable result is a contaminated supply. Addicts, desperate for cash, lie about their blood-borne diseases. There’s almost no way to screen them out.