> * You state "/b/ does not mutate to zero". But the chronology of Pict
> kings (pulled from both the AU and Chronicum Pictorum) suggests that with
> these patronyms, it probably does. One goes from "Bili" to "mac Bhile" to
> "mac Deir Ile" over the course of 40 years.
Der Ile looks like simply a Gaelicization of Brittonic Derelei (the root of
which is perhaps the same as the Der- in the Breton personal names Dergen
and Deroch). The second syllable is just a suffix (compare OW Guoid-el
"Irishman"), and not a lenited form of the name Beli/Bili.
- Chris Gwinn