Jesus was the first to do it! He set an example for us all to follow - he gave his blood as an atoning sacrifice. Blood has many uses and although we shall never be called to give blood as an atoning sacrifice, there is an opportunity to save someone's life by blood transfusions.
Petrol v Diesel
Because Britain has many thousands of immigrants (both legal and illegal) of all ethnicities, they have been asked to donate some of their blood because it is more likely to be compatible than the blood of Englishmen. It can be likened to putting diesel in a petrol engine!
Professor Klaus Von Klott from Nosferatu Haematology Laboratory in Berlin, told In Seine News;
"For many years, ve haf been researching ze reaction of blood cells in newly transferred blood and ze studies reveal that ze patient wiv ze similar ethnic background iz likely to recover far more quickly zan someone who isn't."
Requesting blood from some people does present real problems; Jehovah's Witnesses will not take blood and neither will they give it; members of the Royal Family will not give it because it's the wrong colour - blue. Tax Collectors, Politicians and certain ageing pop stars are also exempt because it is well known that you cannot get blood out a stone!