Ian,
It can be seen from that link I posted above, that the shepherds counting resembles the Brythonic Celtic counting most closely, particularly in the words Pethera, Pimp and Dick.

Apart from the Celtic languages, the only other ones with the K to P sound shift which results in Pethera from the assumed Proto_Indo_European *kwetwores (e.g. Quatre in French) appear to be Italic (Oscan, Umbrian)
and



Whether it came via the Norse I don't know, but the Normans (?Northmen) were decendents of the Vikings who settled in Normandy, and maybe picked it up from there?