Last week I was invited to give platelets instead of normal blood.
In the world of blood donation, this is an upgrade to Club Class. Instead of lying on a temporary couch in Brixton Town Hall, platelet donation means sitting in a high-tech chair watching TV in Tooting.
Platelets are the blood cells that handle clotting. If you've got good blood, you have plenty to spare, and if you haven't got enough, you are in danger of bleeding to death. People who aren't making enough platelets need them, including some premature babies and people having chemotherapy.
Extracting them is more complex than normal blood donation - they take the blood out of your vein, extract the platelets, and put the rest back in - a bit like the dialysis that kidney patients have.
It takes an hour and a half or so, during which time you sit tight, plugged into the machine, in the kind of Club Class airline seat people like me can only dream of. With plenty of leg room, too - with smiling people bringing you snacks.
The donation centre is a pleasant bike ride for me, across Tooting Common.
I was looking forward to this. But my veins let me down.
Club Class blood doners get slightly bigger needles stuck in them apparently (though I couldn't see the difference) - and my veins proved big but unwilling to co-operate with this sort of treatment. We got three samples out of one arm, and none out of the other.
It's a shame, really - apart from my awkward veins, the experience was very pleasant, and I'd recommend it to anyone else.
The only other drawback is that, unlike other Club Class activities, when you come down you're still in Tooting.