I am surprised that no one has picked up the original spelling
i.e.Llaniddel. It is still shown as such on older maps ( also see Kelly's
Directory on line) and I remember local
people who always called it Llaniddel.
As a point of interest I understand this can be roughly translated as Place
of Iddel (pronounced Ithel)so Ithel's place?
It seems that it was found easier to say Llanhilleth than Llaniddel
by the large numbers of non Welshspeakers who came to work at the
Collieries
and Aberbeeg railway junction.
So who was Ithel?
It is an old Welsh name still used as a first name for boys.
There were "Kings of Gwent" in 7th and 8th Century named Ithel. Whether they
were connected in any way is of course another matter.
However , there are also still a few other mysteries about St Illtyd's
Church the ancient building still there. e.g the two tumuli nearby and
the name on old maps Castell Italiorum
Christchurch Aberbeeg replaced St Illtyd's as the Parish Church in 1910.
St Mark,s was built 1898.
AL