Apparently this is not a good haemaglobin level to have. It can cause a degree of lethargy and light-headedness. In fact most people at this level can barely function. My body it seems has adapted to a massively reduced amount of oxygen but hey - still not good.
However 24 hours later, 3 more units of the finest A+ (again hoping that the amazing people that donated are good with their grammar!), and the dizziness has gone and walking upstairs no longer feels like a marathon. Rather a splendid result I say.
Incidently for those that were wondering - the normal level is above 11. Ooops.
I'm glad the energy levels have improved as I am doing the dreaded Heathrow departure gate ordeal later. It never ends well.