If you mean the claim that there has been assisted euthanasia of terminally ill children in the UK, it originates with Dr. Michael Irwin, an assisted euthanasia proponent, made in a radio show; and elicited this reaction:

PressTV - UK Health Secretary orders probe into child euthanasia

Health Secretary Jeremy Hunt ordered the probe and pledged to investigate "whether the law was broken" after retired GP Michael Irwin claimed during a debate on LBC radio that UK medics illegally helped two sick children to die.

The retired doctor said that this has occured "in this country, very quietly. I know of one or two children over the last few years,"  adding, "It has been done under the pretext of what we call Double Effect where the child has been given huge doses of painkillers and so on, in order to relieve discomfort, pain and other symptoms."

_{*Lunatic*, n.
One whose delusions are out of fashion.}