In the list of Pict kings (Chronicum Pictorum) there is a "Bredei filius
Bili", also shown as "Brude filius File" who died in 693. Does this not
demonstrate that the "b" has mutated to the fricative "bh"? He is followed
shortly thereafter by "Bredei filius Derelei" and "Nechtan filius Derelei",
which I would interpret as "son of daughter of Beli", where the fricative
"bh" has now mutated to be silent. This inheiritance of the crown through
the female line (through the daughter of Bili to a grandson) would be in
keeping with Pict tradition as described by ancient historians.
> Either of these is quite intriguing. Is the name found in the
> medieval texts? And if so, where?
Ó Corráin & Maguire list "Der Bile" and "Derbiled" as medieval
saints. DIL cites both of these s.v. "Darbile" from "Félire
Oengusso" and other religious texts.