The entire letter is here:
It is not yet generally accepted that measles can be a dangerous illness. Believe me, it is. In my opinion parents who now refuse to have their children immunised are putting the lives of those children at risk. In America, where measles immunisation is compulsory, measles like smallpox, has been virtually wiped out.
Here in Britain, because so many parents refuse, either out of obstinacy or ignorance or fear, to allow their children to be immunised, we still have a hundred thousand cases of measles every year. Out of those, more than 10,000 will suffer side effects of one kind or another. At least 10,000 will develop ear or chest infections. About 20 will die.
LET THAT SINK IN.
Every year around 20 children will die in Britain from measles.
So what about the risks that your children will run from being immunised?
They are almost non-existent. Listen to this. In a district of around 300,000 people, there will be only one child every 250 years who will develop serious side effects from measles immunisation! That is about a million to one chance. I should think there would be more chance of your child choking to death on a chocolate bar than of becoming seriously ill from a measles immunisation.
So what on earth are you worrying about? It really is almost a crime to allow your child to go unimmunised.