Where does "ta!" come from?

Where does the expression "ta" come from?

Wikipedia has only this to say:

"ta!", slang, Exclam. Thank you! {Informal}, an expression of gratitude

but no additional information or links about its genesis.

I have only ever heard it from englishmen and -women. Is it used anywhere else in the world? How did it come about? What is its history?

Solution 1:

Online Etymology Dictionary says:

ta: 1772, "natural infantile sound of gratitude" [Weekley].

Although possibly originating from the imitative of baby talk, this is in widespread use in the North of England and Wales as an informal "thanks" amongst adults.

American Heritage Dictionary of the English Language says:

ta: Chiefly British
Used to express thanks.
ETYMOLOGY:
Baby-talk alteration of "thank you".

Solution 2:

My compact version of The Oxford English Dictionary lists it as "An infantile word expressing thanks," and dates its first reference from 1772, unless my eyes deceive me (I am momentarily unable to locate the magnifying glass that came with the tome).

Edit:

Thank god for Eric Partridge. He quotes the same OED reference, only in larger type. Here is the entry:

Ta!; rarely taa! Thanks!: coll., orig. and mainly nursery: 1772, Mrs Delany, 'You would not say "ta" to me for my congratulation,' O.E.D. Ex a young child's difficulty with th and nks.