How old is the term "child minder"?

I was interested in finding out when the term child minder was first used.

This Google ngram for "child minder,childminder" shows that the term (with or without a space) had basically no usage at all until 1970. It had a small amount of usage between 1970–1975, and after 1975, the version without a space ("childminder") became much more popular.

The term seems to be slightly later and still slightly less popular than the term "babysitter", according to this ngram (which was restricted to British English):

The earliest Google Books result claims to be from 1949, but I find the dating on that document dubious because it says it's a supplement, and may have been published much later. It's not possible to verify the date using Google Books. There is another example from 1963 which seems less dubious because you can barely make out the date (1964) on the title page image.

In conclusion, the term seems to have become popular in the early 1970s, although there appear to be a small number of instances from before that period, as early as 1963, or possibly as early as 1949.

The British term 'childminder' (written as one word), refers to a person who looks after a child in their own home for payment. (Oxford Dictionary of English - not OED).

The word is given official recognition in law. Such people have to be registered and meet fairly rigorous standards both personal and in terms of the premises of their home (safety features etc). When registered they are known as 'Registered Childminder'

Reg Childminders have to meet far higher standards than mere 'babysitters' who require no qualifications. For example Childminders must possess at least a Level 2 qualification in child care. They are regulated and inspected by Ofsted, a government inspector of educational and nursery establishments.

None of this tells you when the word Childminder began to be used, but registration appears to have been introduced in Britain by the Infant Life Protection Act of 1872.