Wirt Sikes in British Goblins gives a full account of a plentyn-newid, or Welsh changeling, left by the Tylwyth Teg in exchange for the beautiful human child which they coveted. The Welsh changelings differed very little from those elsewhere, and received the same harsh treatment. Sikes says:

The plentyn-newid has the exact appearance of the stolen infant at first; but its aspect speedily alters. It grows ugly of face, shrivelled of form, ill-tempered, wailing, and generally frightful. It bites and strikes, and becomes a terror to the poor mother. Sometimes it is idiotic; but again it has a supernatural cunning, not only impossible in a mortal babe, but not even appertaining to the oldest heads, on other than fairy shoulders.

Among the cruelties practised to drive away the fairy was the placing of the child on a heated shovel, as in Ireland, where a baby was actually killed by the neighbours in the 19th century. A Welsh method is to bathe the child in a solution of fox-gloves. This is said to have killed a Caernarvonshire baby in 1858.

The brewery of eggshells is used in Wales as in Scotland to discover a changeling, or sometimes porridge is made in an eggshell, or a blackbird roasted to make a dinner for fifteen reapers, and the changeling's exclamation, 'I have seen the acorn before the oak', is as common in Wales as in Scotland. These close resemblances in Celtic areas which have been long separated seem to mark the changeling beliefs as very early ones.

[Motif: F321.1]