The stories are set mainly in the Berkshire countryside, at the farmhouse home of the children's grandmother, a Scottish-born woman named Mrs Hawthorne.
John and Mary are educated at home by a governess called Miss Rose Brown, although they spend about half their time in Rome, and indeed are bilingual in English and Italian.
Smockfarthing carries a full complement of servants, including Mrs. Dyer the cook, Ellen the parlourmaid, Lizzie (whom the children call Lisetta) the maid, and Edie Kittiwake, the nurse.
(One can only assume that Grace James wished to appeal to a constantly fresh readership, although children of the 1960s could possibly have found it rather odd that John and Mary would still have a governess and maids running around after them, in that era.)
The John and Mary stories involve the children doing fairly normal and day-to-day things within their environment (mainly the countryside), although James makes sure that they meet unusual people and have adventures along the way.