From a french book published in 1914 by a famous hygienist
" A new culinary religion was born in England. This is about nothing less than eating everything raw. Listen carefully. The protagonists of this new diet - a natural one, if such a thing ever existed - do not simply eat their MEAT raw , but they take, under this form, everything that we eat.
It is well known that raw meat can be easily digested, contrary to cooked meat........"
Unfortunately there is no direct reference to an english source in this book, but there are a number of indirect references where I might be able to locate the primary source. I will keep you posted in case I can find something