Daniel Carter - Who He?

I thought my copy of Meic Stephens' Oxford Companion to the Literature of Wales was pretty well-thumbed but, somehow or other, one entry of Radnorshire interest managed to escape attention for the last 25 years.

Daniel Carter, it seems, was the author of a book-length descriptive poem published in Llanidloes in 1863 entitled Rhaiadr Gwy. Now this poem, the Radnorshire Museum have a copy, may well be worth reading for its "notes historical and topographical, antiquarian and archaeological." The Oxford Companion also mentions two other works - The Legend of Devil's Bridge and The Rose of Pont Vathew - although these have so far escaped the notice of the internet.

So who was this Daniel Carter, whose "life's work" was as Master of the Foundation Grammar School at Rhayader, an institution which seems to be as obscure as Carter's connection with the town? In 1840 when he wrote Rhaiadr Gwy he was living, by his own account, at Ffynnon Fair Cottage in the town. His full name was Daniel Pepper Carter, born in Lambeth around 1808 with no apparent connection to Wales. I can first spot him in the 1851 Census when he was living in Newtown and described as a teacher of languages. His wife Elizabeth, they had recently married, was from Hay, or more likely Betws Clyro. By 1861 the couple had moved to Ashby de la Zouch and Carter had promoted himself to be a professor of languages. In 1871 he is at Hereford, an author-miscellaneous and blind. Carter died a few weeks later on 30th June 1871.

Does someone know more about the elusive Mr Carter or his Foundation Grammar School at Rhayader?