Note: The linked review by Kirkus begins, "When four English children are transported through time, via the magic key to an old Scottish keep, they react very differently: ..." It specifies both 1460 and "the 22nd-century ruins of technological civilization". The children are 5 to 14 years old. The 15th-century episode makes nothing of their English "nationality which is, after all, the same as that of the villagers' enemies."